Quick Facts
In full:
Mark Steven Kirk
Born:
September 15, 1959, Champaign, Illinois, U.S. (age 65)
Political Affiliation:
Republican Party

Mark Kirk (born September 15, 1959, Champaign, Illinois, U.S.) is an American politician who was elected as a Republican to the U.S. Senate in 2010 and represented Illinois from 2011 to 2017. He previously served in the U.S. House of Representatives (2001–10).

Kirk attended the National Autonomous University of Mexico in Mexico City before graduating cum laude from Cornell University (B.A., 1981). He then earned a master’s degree (1982) from the London School of Economics and Political Science, during which time he was an assistant to a member of the House of Commons. After graduating, Kirk remained in London for a year, teaching at a private school. He later studied law at Georgetown University (Juris Doctor degree, 1992). During that time, Kirk entered the U.S. Naval Reserve (1989–2013), where he worked as an intelligence officer and later served in noncombat roles in air campaigns in Yugoslavia and Iraq; he retired with the rank of commander.

Kirk’s interest in politics continued after college, and from 1984 to 1990 he served on the staff of U.S. Rep. John Porter. After working as a special assistant in the U.S. State Department (1992–93), he practiced law for several years. He then served as counsel to the House International Relations Committee (later called House Committee on Foreign Affairs) until 1999, when he returned to Illinois to run for the U.S. House of Representatives. After narrowly winning the election, he took office in 2001. That same year Kirk married Kimberly Vertolli; the couple divorced in 2009.

In 2010 Kirk ran in a special election to fill the U.S. Senate seat that had been held by Barack Obama and then appointee Roland Burris. Despite some controversies—notably, Kirk misstated some facts of his military service—he won the close election and took office soon thereafter. In January 2012 Kirk suffered a major stroke that required surgery and a lengthy rehabilitation. He returned to the Senate in January 2013.

While in Congress, Kirk developed a reputation as a moderate Republican. Unlike many in his party, he supported abortion rights, marriage equality, and gun-control legislation. However, on fiscal matters he generally adopted a more-conservative stance. He opposed efforts to raise the minimum wage, and he pushed for tax cuts. Kirk also was active in efforts to protect the Great Lakes.

In 2016 Kirk faced a tough reelection bid, facing off against Democratic challenger Tammy Duckworth, a veteran of the Iraq War who had lost both legs there. His campaign struggled to gain momentum as he lost the support of some Republicans for his sharp criticism of the party’s presidential candidate, Donald Trump. Then, just days before the election, Kirk faced a backlash after seeming to question during a debate both Duckworth’s heritage as well as her family’s military service. In the November election, Kirk was easily defeated, and he left office in 2017.

Gregory Lewis McNamee The Editors of Encyclopaedia Britannica
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United States Senate

United States government
Quick Facts
Date:
1789 - present
Areas Of Involvement:
Congressional Term Limits

United States Senate, one of the two houses of the legislature (Congress) of the United States, established in 1789 under the Constitution. Each state elects two senators for six-year terms. The terms of about one-third of the Senate membership expire every two years, earning the chamber the nickname “the house that never dies.”

Constitutional framework

The role of the Senate was conceived by the Founding Fathers as a check on the popularly elected House of Representatives. Thus, each state, regardless of size or population, is equally represented. Further, until the Seventeenth Amendment of the Constitution (1913), election to the Senate was indirect, by the state legislatures. They are now elected directly by voters of each state.

The Senate shares with the House of Representatives responsibility for all lawmaking within the United States. For an act of Congress to be valid, both houses must approve an identical document.

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The Senate is given important powers under the “advice and consent” provisions (Article II, section 2) of the Constitution: ratification of treaties requires a two-thirds majority of all senators present and a simple majority for approval of important public appointments, such as those of cabinet members, ambassadors, and justices of the Supreme Court. The Senate also adjudicates impeachment proceedings initiated in the House of Representatives, a two-thirds majority being necessary for conviction.

Organization and powers

As in the House of Representatives, political parties and the committee system dominate procedure and organization. Each party elects a leader, generally a senator of considerable influence in his or her own right, to coordinate Senate activities. The leader of the largest party is known as the majority leader, while the opposition leader is known as the minority leader. The Senate leaders also play an important role in appointing members of their party to the Senate committees, which consider and process legislation and exercise general control over government agencies and departments. The vice president of the United States serves as the president of the Senate but can vote only in instances where there is a tie. In the vice president’s absence, the president pro tempore—generally the longest-serving member from the majority party—is the presiding officer of the Senate.

Sixteen standing committees are grouped mainly around major policy areas, each having staffs, budgets, and various subcommittees. The chair of each committee is a member of the majority party. Among important standing committees are those on appropriations, finance, government operations, foreign relations, and the judiciary. Thousands of bills are referred to the committees during each session of Congress, though the committees take up only a fraction of these bills. At “mark-up” sessions, which may be open or closed, the final language for a law is considered. The committees hold hearings and call witnesses to testify about the legislation before them. Select and special committees are also created to make studies or to conduct investigations and report to the Senate; these committees cover aging, ethics, Indian affairs, and intelligence.

The smaller membership of the Senate permits more extended debate than is common in the House of Representatives. To check a filibuster—endless debate obstructing legislative action—three-fifths of the membership (60 senators) must vote for cloture. (In 2013 the Senate rule for invoking cloture was reinterpreted to permit cloture by majority vote for debate regarding all presidential nominations except those to the Supreme Court, and in 2017 the rule was similarly reinterpreted for Supreme Court nominations.) If the legislation under debate would change the Senate’s standing rules, cloture may be invoked only on a vote of two-thirds of those present. There is a less elaborate structure of party control in the Senate; the position taken by influential senators may be more significant than the position (if any) taken by the party.

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The constitutional provisions regarding qualifications for membership of the Senate specify a minimum age of 30, citizenship of the United States for nine years, and residence in the state from which elected.

U.S. senators

The table provides a list of current U.S. senators.

United States Senate, 119th Congress
Party totals: Republicans (R) 53; Democrats (D) 45; Independents (I) 2
state senator (party) service began term ends
1Martha McSally was appointed in December 2018 and took office the following month to fill the vacancy caused by the resignation of Jon Kyl, who had been appointed in September 2018 to fill the vacancy caused by the death of John McCain. Mark Kelly won a special election in November 2020 and took office in December.
2Alex Padilla was appointed in December 2020 and took office in January 2021 to complete the term of Kamala Harris, who resigned to become vice president.
3Michael Bennet was appointed in January 2009 to complete the term of Ken Salazar, who resigned to become secretary of the interior.
4Ted Kaufman was appointed in January 2009 to replace Joe Biden, who resigned to become vice president. In 2010 Chris Coons won a special election to complete the term.
5Ashley Moody was appointed in January 2025 to replace Marco Rubio, who resigned to become secretary of state. A special election was scheduled for 2026.
6Kelly Loeffler was appointed in December 2019 and took office in January 2020 to fill the vacancy caused by the resignation of Johnny Isakson. Raphael Warnock won a special election in November 2020 and took office in January 2021.
7Brian Schatz was appointed in December 2012 to fill the vacancy caused by the death of Daniel Inouye.
8William Cowan was appointed in January 2013 and took office in February to replace John Kerry, who resigned to become secretary of state. In July 2013 Ed Markey won a special election to complete the term.
9Tina Smith was appointed in December 2017 and took office in January 2018 to fill the vacancy caused by the resignation of Al Franken.
10Roger Wicker was appointed in December 2007 to fill the vacancy caused by the resignation of Trent Lott.
11Cindy Hyde-Smith was appointed in March 2018 and took office in April to fill the vacancy caused by the resignation of Thad Cochran.
12Peter Ricketts was appointed in January 2023 to fill the vacancy caused by the resignation of Ben Sasse.
13Jeff Chiesa was appointed in June 2013 to fill the vacancy caused by the death of Frank R. Lautenberg. In October 2013 Cory Booker won a special election to complete the term.
14Kirsten Gillibrand was appointed in January 2009 to replace Hillary Rodham Clinton, who resigned to become secretary of state.
15Jon Husted was appointed in January 1996 to replace J.D. Vance, who resigned to become vice president. A special election was scheduled for 2026.
16Ron Wyden was elected in January 1996 to complete the term of Bob Packwood, who resigned in 1995.
17Tim Scott was appointed in December 2012 and took office in January 2013 to fill the vacancy caused by the retirement of Jim DeMint.
18John Barrasso was appointed in June 2007 to fill the vacancy caused by the death of Craig Thomas.
Alabama Tommy Tuberville (R) 2021 2027
Katie Boyd Britt (R) 2023 2029
Alaska Lisa Murkowski (R) 2002 2029
Dan Sullivan (R) 2015 2027
Arizona Mark Kelly (D) 20201 2029
Ruben Gallego (D) 2025 2031
Arkansas John Boozman (R) 2011 2029
Tom Cotton (R) 2015 2027
California Alex Padilla (D) 20212 2029
Adam Schiff (D) 2024 2031
Colorado Michael Bennet (D) 20093 2029
John W. Hickenlooper (D) 2021 2027
Connecticut Richard Blumenthal (D) 2011 2029
Chris Murphy (D) 2013 2031
Delaware Chris Coons (D) 20104 2027
Lisa Blunt Rochester (D) 2025 2031
Florida Rick Scott (R) 2019 2031
Ashley Moody (R) 20255 2029
Georgia Jon Ossoff (D) 2021 2027
Raphael Warnock (D) 20216 2029
Hawaii Mazie Hirono (D) 2013 2031
Brian Schatz (D) 20127 2029
Idaho Mike Crapo (R) 1999 2029
Jim Risch (R) 2009 2027
Illinois Dick Durbin (D) 1997 2027
Tammy Duckworth (D) 2017 2029
Indiana Todd Young (R) 2017 2029
Jim Banks (R) 2025 2031
Iowa Chuck Grassley (R) 1981 2029
Joni Ernst (R) 2015 2027
Kansas Jerry Moran (R) 2011 2029
Roger Marshall (R) 2021 2027
Kentucky Mitch McConnell (R) 1985 2027
Rand Paul (R) 2011 2029
Louisiana Bill Cassidy (R) 2015 2027
John Kennedy (R) 2017 2029
Maine Susan Collins (R) 1997 2027
Angus King (I) 2013 2031
Maryland Chris Van Hollen (D) 2017 2029
Angela Alsobrooks (D) 2025 2031
Massachusetts Elizabeth Warren (D) 2013 2031
Ed Markey (D) 20138 2027
Michigan Gary Peters (D) 2015 2027
Elissa Slotnik (D) 2025 2031
Minnesota Amy Klobuchar (D) 2007 2031
Tina Smith (D) 20189 2027
Mississippi Roger Wicker (R) 200710 2031
Cindy Hyde-Smith (R) 201811 2027
Missouri Josh Hawley (R) 2019 2031
Eric Schmitt (R) 2023 2029
Montana Steve Daines (R) 2015 2027
Tim Sheehy (R) 2025 2031
Nebraska Deb Fischer (R) 2013 2031
Pete Ricketts (R) 202312 2026
Nevada Catherine Cortez Masto (D) 2017 2029
Jacky Rosen (D) 2019 2031
New Hampshire Jeanne Shaheen (D) 2009 2027
Maggie Hassan (D) 2017 2029
New Jersey Cory Booker (D) 201313 2027
Andy Kim (D) 2025 2031
New Mexico Martin Heinrich (D) 2013 2031
Ben Ray Luján (D) 2021 2027
New York Chuck Schumer (D) 1999 2029
Kirsten Gillibrand (D) 200914 2031
North Carolina Thom Tillis (R) 2015 2027
Ted Budd (R) 2023 2029
North Dakota John Hoeven (R) 2011 2029
Kevin Cramer (R) 2019 2031
Ohio Bernie Moreno (R) 2025 2031
John Husted (R) 202515 2029
Oklahoma James Lankford (R) 2015 2027
Markwayne Mullin (R) 2023 2029
Oregon Ron Wyden (D) 199616 2029
Jeff Merkley (D) 2009 2027
Pennsylvania John Fetterman (D) 2023 2029
David McCormick (R) 2025 2031
Rhode Island Jack Reed (D) 1997 2027
Sheldon Whitehouse (D) 2007 2031
South Carolina Lindsey Graham (R) 2003 2027
Tim Scott (R) 201317 2027
South Dakota John Thune (R) 2005 2029
Mike Rounds (R) 2015 2027
Tennessee Marsha Blackburn (R) 2019 2031
Bill Hagerty (R) 2021 2027
Texas John Cornyn (R) 2002 2027
Ted Cruz (R) 2013 2031
Utah Mike Lee (R) 2011 2029
John Curtis (R) 2025 2031
Vermont Bernie Sanders (I) 2007 2031
Peter Welch (D) 2023 2029
Virginia Mark Warner (D) 2009 2027
Tim Kaine (D) 2013 2031
Washington Patty Murray (D) 1993 2029
Maria Cantwell (D) 2001 2031
West Virginia Shelley Moore Capito (R) 2015 2027
Jim Justice (R) 2025 2031
Wisconsin Ron Johnson (R) 2011 2029
Tammy Baldwin (D) 2013 2031
Wyoming John Barrasso (R) 200718 2031
Cynthia M. Lummis (R) 2021 2027

Women in the Senate

The Editors of Encyclopaedia Britannica
This article was most recently revised and updated by Amy Tikkanen.
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