[8] Hart was an active grassroots volunteer in her party in Western Pennsylvania from her days as a student at Washington & Jefferson College.

In her first run for office, Hart defeated an incumbent in a senate district that included parts of Allegheny, Westmoreland and Armstrong counties.

In November 2000, Hart was elected to the House of Representatives from the Fourth District of the State of Pennsylvania, winning an open seat previously held by a Democrat.

"[11] Hart is Roman Catholic and was a legislative leader on anti-abortion issues, such as opposition to federal funding for embryonic stem cell research.

In January 2006, she addressed an anti-abortion rally in Washington, D.C., urging young people who oppose abortion to enter public service.

[citation needed] She opposed abortions for rape and incest cases, and sponsored laws to promote assistance to women and children such as safe haven laws which prevent mothers from being charged with abandonment when they bring their child to a safe place such as a hospital or police station to allow the child to be adopted.

As the 2006 campaign season approached, Hart's congressional seat was not considered vulnerable, and Hart was described in media accounts as a "rising star" in Republican politics, who had never lost an election and who had demonstrated a unique ability to appeal to non-conservative voters even while maintaining a generally conservative voting record.

[12] In late 2005, her predecessor in the House of Representatives, Democrat Ron Klink, publicly mulled over the possibility of challenging Hart for his old seat.

Jason Altmire, a 38-year-old health care executive and political unknown (and, by coincidence, a neighbor of Hart's brother),[13] ultimately won the Democratic nomination for the seat.

[14] Altmire's continued to climb as Hart's stalled, and five days before the November 7, 2006, election, the Cook Political Report altered its rating of the race from "Likely Republican" to "Toss up.

Despite speculation that retired athlete and former gubernatorial candidate Lynn Swann would run for the seat,[18] Hart was unopposed for the Republican nomination.

She later returned to her original law firm, Hergenroeder Rega Ewing & Kennedy in 2017 to work with a group of attorneys with whom she had begun her legal career.

[20] Hart sought to retake her state senate seat in a 2012 special election triggered when her successor, Jane Orie, was forced to resign after being convicted of corruption and forgery.