Kyrsten Lea Sinema, born July 12, 1976, in Tucson, Arizona, is an American lawyer, former social worker, and politician who represented Arizona in the U.S. House of Representatives from 2013 to 2019 and in the U.S. Senate from 2019 to 2025. She was the first woman elected to the Senate from Arizona, the first openly bisexual member of Congress, and the first Democrat to win an Arizona Senate seat in a generation. After most of her career as a Democrat, she registered as an independent in December 2022, continued to caucus with Democrats, and declined to seek a second Senate term in 2024. Democrat Ruben Gallego won the seat that November.
Sinema’s early life is the story she has told most often. She was born to Marilyn Wiley and Dan Sinema, an attorney, into a middle-class Mormon household. After her parents divorced in the early 1980s, her mother remarried and moved the family to DeFuniak Springs, Florida. When her stepfather lost work and the bank foreclosed on their home, they spent about three years in a former gas station. Sinema has said the building lacked running water and electricity for part of that time, and that the family relied on church aid and federal food assistance. Some reporting later questioned details of the account; Sinema has answered that she described what she remembered living through. The episode, she has said, pushed her toward social work and public life.
Ambition showed early. At 16 she graduated as valedictorian from Walton High School. At 18 she finished a bachelor’s degree at Brigham Young University, then left both Utah and the Church of Jesus Christ of Latter-day Saints. She has since identified as religiously unaffiliated. She returned to Arizona, worked as a school social worker in Phoenix, and earned a Master of Social Work from Arizona State University in 1999. A J.D. from ASU’s College of Law followed in 2004; a Ph.D. in justice studies in 2012; and later an M.B.A. She practiced as a criminal defense lawyer, taught as an adjunct at ASU, and has remained connected to the university’s School of Social Work. She was briefly married to Blake Dain and later divorced. She also completed an Ironman triathlon.
Her first politics were not Democratic. In 2000 she worked on Ralph Nader’s presidential campaign and was active with Arizona’s Green Party, speaking in a progressive register on LGBT rights, the Iraq War, and economic inequality. A 2002 bid for the Arizona House failed. In 2004 she joined the Democratic Party, arguing that working outside the two-party system was not producing results. That year she won a Phoenix-area seat in the state House, serving from 2005 to 2011 and rising to assistant Democratic leader. She served briefly in the Arizona Senate from 2011 to 2012. In the legislature she began building a reputation for working across the aisle even as she came out as bisexual. In 2009 she published Unite and Conquer: How to Build Coalitions That Win and Last. A later academic book, Who Must Die in Rwanda’s Genocide?: The State of Exception Realized (2015), grew out of her doctoral work.
Redistricting created Arizona’s 9th Congressional District, a competitive Phoenix-area seat. Sinema won it in 2012 over Republican Vernon Parker and became the first openly bisexual member of the U.S. House. She won two more terms. In the House she sat on Financial Services, moved toward the center, and often presented herself as a dealmaker rather than a partisan combatant—an identity she would refine, and that would later alienate much of her original base.
In 2018 she ran for the open Senate seat being vacated by Republican Jeff Flake and defeated Republican Martha McSally. She became Arizona’s first woman senator and the first Democrat to hold the seat since the mid-1990s. She took the oath on a copy of the Constitution rather than a Bible. In a 50–50 and then narrowly Democratic Senate, she and West Virginia’s Joe Manchin became the chamber’s most closely watched centrists. She helped negotiate the 2021 bipartisan infrastructure law with Republican Rob Portman and a group of ten senators. She worked on the Bipartisan Safer Communities Act after the Uvalde shooting, coauthoring language aimed at keeping guns from domestic abusers. With Republicans and Democrats she helped pass the Respect for Marriage Act, which wrote federal recognition of same-sex and interracial marriages into statute while adding religious-liberty protections. She also helped keep the CHIPS and Science Act from collapsing, a bill that later fed semiconductor investment in Arizona.
The same years made her a target on the left. She opposed changing Senate rules to weaken the legislative filibuster, including on voting-rights bills, arguing that a 60-vote threshold forced consensus and that ending it would invite one-party rule whenever majorities flipped. She voted against attaching a federal minimum-wage hike to a reconciliation bill and extracted concessions on the Inflation Reduction Act, including changes that dropped or altered tax provisions aimed at private-equity and hedge-fund managers. Progressive groups organized against her. Arizona Democrats censured her. She answered that she had promised voters an independent voice, not a party line.
On December 9, 2022, days after Democrats secured a 51-seat majority, she announced she was leaving the party. “I’ve never fit neatly into any party box,” she wrote. She kept her committee assignments and continued to organize with Democrats, so the chamber’s majority math did not flip. The switch did not repair her standing with Arizona Democrats, who already had a primary challenger in Ruben Gallego. Fundraising lagged. In March 2024 she said she would not run again. “I believe in my approach. But it’s not what America wants right now,” she said, adding that she chose “civility, understanding, listening, working together to get stuff done.” In a December 2024 farewell speech she again defended the filibuster and listed the infrastructure, marriage, chips, and gun bills as proof that deals were still possible without tearing up Senate rules. She left office on January 3, 2025.
After the Senate she moved quickly into private roles. In January 2025 she joined Coinbase’s Global Advisory Council. In March she became a senior adviser at the global law firm Hogan Lovells in Washington, working on regulatory and public-affairs issues around artificial intelligence, crypto, and related industries; she said she would not register as a lobbyist. She has co-founded or co-chaired an AI Infrastructure Coalition, been associated with an Arizona Business Roundtable focused on data centers and investment, lectured at ASU, and written as a contributing columnist. She has spoken favorably about aspects of the second Trump administration’s AI and crypto posture and about elements of Robert F. Kennedy Jr.’s “Make America Healthy Again” agenda, and she has advocated research into the psychedelic ibogaine for mental-health treatment. Critics describe a further shift to the right and a revolving door into industry advocacy; she describes continuity with the dealmaking she practiced in office.
In 2026 her private life returned to the headlines. Heather Ammel sued her in federal court in North Carolina under the state’s “alienation of affection” statute, alleging that Sinema’s relationship with Matthew Ammel, a former member of Sinema’s security detail and a U.S. Army veteran, broke up the Ammels’ marriage. Sinema has acknowledged a romantic relationship but has denied that it began while he was still married. A judge allowed the suit to proceed, citing text messages sent while Ammel was in North Carolina. In September 2026 Ammel was arrested and accused of causing more than $200,000 in damage to Sinema’s Cave Creek home after a dispute over a social-media video. Those matters were unresolved as of late September 2026.
Sinema’s public image was always part of the story: vivid clothes and hair, a theatrical thumbs-down on the Senate floor that became a meme, a taste for endurance sports and for being slightly out of step with her party. The substance underneath was a long ideological migration—from Green Party activist and social worker to Democratic legislator, to House moderate, to Senate swing vote, to independents who left office arguing that the country no longer rewarded compromise. Supporters credit her with tangible statutes on infrastructure, semiconductors, marriage, and guns, and with holding a purple-state seat that Democrats had not won in decades. Detractors see a politician who used a narrow majority to block her own party’s priorities, then cashed the resulting brand in Washington and industry. Both readings start from the same record: a career built on refusing to stay in the box where it began.