Gabrielle Giffords, a rising star of the Democratic Party in the House, was elected to Congress in 2006 and built a reputation as a pragmatic moderate who supported President Obama's health care reform package in 2010.
She is part of the Blue Dog coalition of centrist Democrats and, as a former executive in her family's tire dealership, was a strong proponent of small-business interests.
Facing a tough re-election battle in 2010, Giffords, 40, was one of the candidates targeted for defeat by Sarah Palin and the tea party movement.
In March, her Tucson office was vandalized a few hours after the House vote to approve the health care law, with someone shooting out a glass door and window.
Her 2010 Republican opponent, former Marine Sgt. Jesse Kelly, 29, held campaign events under the slogan "Help remove Gabrielle Giffords from office" and invited his supporters to "shoot a fully automatic M16 with Jesse Kelly."
Giffords won the election by 2 percentage points.
She often touted her support of the Second Amendment to voters and said she had been a longtime gun owner.
Since her re-election, she has been mentioned as a possible Democratic nominee in 2012 for the U.S. Senate seat held by Republican Jon Kyl or for the governor's office in 2014.
Giffords met astronaut Mark E. Kelly, who has piloted space shuttles Endeavour and Discovery, in 2003 while they were serving on a committee in China. They were married in January 2007 while Giffords served on the House Science and Technology space subcommittee. The couple have no children.
Sen. Bill Nelson, D-Fla., chairman of the Senate Commerce Space and Science Subcommittee, said her husband is training to be the next commander of the space shuttle mission slated for April.
Giffords was born June 8, 1970, in Tucson. Early in life, she was inspired by Arizona-born former Supreme Court Justice Sandra Day O'Connor and registered as a Republican when she turned 18.
She graduated from Scripps College in Claremont, Calif., in 1993 with a degree in Latin American history and sociology, and studied in Mexico for a year on a Fulbright scholarship.
In 1996, Giffords received a master's degree in regional planning from Cornell University. She worked for Price Waterhouse in New York for a short time before returning to Tucson in 1996 to take over her family's tire dealership.
She revived the business before selling it in 2000 and then founded a property management business.
In 1999, dismayed by the conservative social positions of the Republican Party, she changed her affiliation to the Democratic Party. A year later, she was elected to the Arizona House of Representations.
In 2002, when she was 32, she became the youngest woman elected to the Arizona State Senate.
When 11-term Republican Rep. Jim Kolbe announced that he would not seek re-election in Arizona's 8th Congressional District in 2006, Giffords mounted a strong primary campaign and won the general election with 54 percent of the vote.
After winning re-election with 54 percent of the vote in 2008, Giffords became a strong advocate of immigration reform. Her district borders Mexico for 114 miles.
Giffords, a solar energy proponent, attended the international climate conference in Copenhagen in December 2009.