BATON ROUGE, La. (CNN) -- Under fire for her handling of Hurricane Katrina and its aftermath and trailing badly in the polls, Louisiana Gov. Kathleen Blanco announced Tuesday that "after much thought and prayer," she has decided not to seek re-election this fall.

"I am choosing to do what I believe is best for my state," the Democratic governor said in a letter to her staff. "I believe there is nothing more important to Louisiana's future than a strong recovery, free from politics."

Blanco's decision opens the way for another prominent Democrat to step forward to try to keep the governorship out of Republican hands. Former U.S. Sen. John Breaux, now a Washington lobbyist, is being mentioned, although the state GOP has already run an ad charging he no longer qualifies as a Louisiana resident because he lives in Maryland.

Democrats had been nervous about Blanco's prospects for re-election, after a Southern and Opinion Research poll in January showed her trailing her chief Republican rival, Rep. Bobby Jindal, by 24 points in a head-to-head matchup.

Blanco, 64, a former teacher who worked her way up through the ranks of state government over two decades, narrowly defeated Jindal in 2003 to become the first woman governor in the state's history. But she came under fire for the state's handling of the Hurricane Katrina disaster in 2005. More recently, a state recovery program called Road Home, which she championed, has been assailed for being overly bureaucratic and too slow in providing rebuilding grants to displaced homeowners.

Under Louisiana's unique open primary system, all candidates, regardless of party, will run against each other in a primary on Oct. 20. If no candidate gets a majority, the top two vote-getters will face each other in a runoff on Nov. 17.