Updated

Former Surgeon General Richard Carmona jumped into the U.S. Senate race in Arizona on Thursday, brandishing the kind of resume that some Democratic leaders believe will appeal to the state's moderate and independent voters.

Carmona served as surgeon general under President George W. Bush, but he was highly critical of the administration after he left, and Democrats have aggressively recruited him to run under their banner. Carmona describes himself as a fierce independent and notes that Republicans in the past had also recruited him to run for office.

The 61-year-old Carmona will attempt to succeed Republican Sen. Jon Kyl, who is retiring. He will face former Arizona Democratic Party chairman Don Bivens in the primary.

Carmona moved back to Tucson after his surgeon general stint. He serves as president of a charity that works with other organizations to improve people's health. He also serves as a professor at the University of Arizona.

In a written announcement, Carmona touted his experience as a Vietnam War medic, trauma surgeon and deputy sheriff as examples of how he had to work to solve problems without regard to political affiliation.

"We never had time from petty squabbles or gamesmanship," said Carmona. "We had to work together to get results because lives were on the line."

As surgeon general Carmona is best known for a report on the dangers of second-hand smoke, and for Congressional testimony that blasted officials in the Bush administration for stymying or delaying reports for political reasons rather than scientific ones. Carmona said back in 2007 that he was told not to talk about certain issues, such as his support for comprehensive sex education that would include abstinence in the curriculum, rather than focusing solely on abstinence.

National Democrats have worked aggressively to recruit Carmona, noting that President Barack Obama and aides to Rep. Gabby Giffords have encouraged Carmona to run. But Bivens has strong ties to local Democratic Party leaders and state Democratic leaders. Bivens said that "while some in DC have selected their candidate for Arizona," he had the support of people such as former Arizona Reps. Harry Mitchell and Ann Kirkpatrick.

"As our senator, I won't become part of the partisan bickering that consumes Washington, but I will never abandon the core principles that made me a lifelong Democrat," said Bivens in a pointed reference to Carmona's boasts of being a registered independent.

Republicans in Washington quickly pitched Carmona as the "hand-picked candidate of the Washington Democratic establishment." They said national Democrats have chosen to create a costly divisive primary by recruiting Carmona.

In a note to employees at Canyon Ranch, Carmona said it was agonizing to think of not working with them on a daily basis. He described himself as a "radical centrist" who would attempt to bring compassionate leadership to the Senate.

Carmona was born and raised in Harlem in New York. He served in Vietnam and was awarded two Bronze Starts and two Purple Hearts. After leaving the Army, he went to college and earned a medical degree. He established the first trauma care system in Southern Arizona.

The winner of the Democratic primary will face a tough general election as well. The favorite is Rep. Jeff Flake. Developer Wilford Cardon has also indicated he will put considerable financial resources into the election and has lent the campaign $815,000, according to the latest quarterly report from the Federal Election Commission.