Virginia Democratic Senator Jim Webb said on Wednesday he will not run for re-election in 2012, hurting chances his party will hold the seat in the state that has taken a Republican turn.
The announcement also dashes prospects for a high-profile rematch between Webb and former Republican Senator George Allen, who is making a bid to regain the seat he lost partly because of a racially insensitive comment he made during his campaign.
Webb won an upset victory in 2006 against Allen, who had been considered a possible contender for the Republican presidential nomination in 2008 until he was criticized for calling a young Democratic operative "macaca," which was seen as a disparaging term.
Considered a moderate Democrat, Webb, a former Navy secretary and one-time Republican, had a high profile on foreign relations and national security issues.
"I have decided to return to the private sector, where I have spent most of my professional life," he said in a statement. But he added that he had "every intention of remaining involved in the issues that affect the well-being and the future of our country."
Democrat Barack Obama carried Virginia in 2008 when he went on to win the presidential election, but two years later Republicans easily swept three statewide offices on the ballot -- governor, lieutenant governor and attorney general.
Republicans made gains nationwide in the 2010 congressional elections, taking control of the House of Representatives and giving Democrats a slimmer majority in the Senate.
Webb's and other recent retirement announcements combined with a turning political tide might make 2012 a tough year for the Democratic Party, said Larry Sabato, director of the Center for Politics at the University of Virginia.
"Because the senators elected in 2006 are coming up this year, naturally there are some very vulnerable Democrats," he told Reuters, describing 2006 as a wave election for Democrats in which they elected some of their more marginal candidates.
"The long and short of it is that (2012 is) going to be a tough year for Democrats," he said, adding that Obama's electoral performance will be critical to whether those vulnerabilities give Republicans more seats in Congress.
Sabato said Democrats will likely try to get Tim Kaine, the former Virginia governor and the party's national chairman, to run for the Senate seat.
After Webb's announcement, White House spokesman Robert Gibbs said on Wednesday he thinks "Virginia is going to be a very competitive state as it was last time in both presidential and Senate elections."