Maine U.S. rep. Chellie Pingree announced Wednesday she is no longer pursuing her campaign for the U.S. Senate. 

Pingree will instead focus on her re-election bid for the 1st Congressional District seat. 

Pingree had been considered the Democratic front-runner for the position that will be vacated by U.S. Sen. Olympia Snowe, R-Maine. Snowe announced last week she was abandoning her re-election bid this year, setting off a scramble of potential candidates eyeing the void.  

"This has been a very difficult decision and I will always be grateful for the tremendous support I’ve received from people all across Maine and around the country," Pingree said in a statement.  

She added, "There is much at stake in this election and although the prospect of running for and possibly serving in the United States Senate was very exciting, in the end I concluded that I will best serve the people of Maine by running for re-election to the House."

Her term expires in January 2013.

While Pingree was considered a favorite to win the Democratic primary, her chances for victory in the general election narrowed when former independent Gov. Angus King entered the race Monday. 

Two national polls, one by Public Policy Polling, showed King had the early edge in a three-way race. The Democratic National Senatorial Committee had also conducted some polling showing similar results, according to a Democratic source.

Pingree's favorability ratings were high and she had the edge in a two-way race. However, in the three-way race with King, polling indicated the margins were thin, and the seat could potentially go to a Republican.

Democrats feared a repeat of a scenario that played out during the 2010 gubernatorial election. During that race Gov. Paul LePage won a narrow three-way race when independent candidate Eliot Cutler split the Democratic and independent vote. Cutler finished a close second. 

King, in a written statement, said he is relieved Pingree dropped out of the race because he "wasn't looking forward to running against a friend."

Pingree's decision to re-enter the 1st Congressional District race will reshape the field there, too. Several Democratic and Republican candidates began gathering signatures to get on the primary ballot. However, several are expected to abandon those efforts now that Pingree is back in. 

Republican state Sen. Jonathan Courtney, R-Springvale, said earlier this week that he will likely stay in the race regardless of Pingree's decision. Courtney earlier this year had originally declined to the enter the race, saying he believed it would be difficult to compete with Pingree's fundraising prowess. 

Meanwhile, the U.S. Senate race could become more crowded with Democrats seeking to boost their profile and give the party base a choice in June. Former Democratic Gov. John Baldacci has been gathering signatures, but his campaign was noncommittal about whether he was staying in the race.

Democratic state Sen. Cynthia Dill of Cape Elizabeth announced that she would continue vying for the Senate. Dill, who has jumped back and forth between the Senate and 1st District race as high-profile candidates entered and dropped out, said in a statement that she was the "only progressive in the race."

Former Secretary of State Matt Dunlap is also vying for the Senate.

On the Republican side, Secretary of State Charlie Summers, former state Senate President Rick Bennett, Attorney General William Schneider, state Sen. Deborah Plowman of Hampden and state Treasurer Bruce Poliquin are all gathering signatures to get on the ballot.

The PPP poll released Tuesday showed that Summers and Poliquin have the best name recognition. However, both have higher unfavorable ratings among those polled.

Republican insiders appear to be split between Schneider and Bennett, a former board member of the Maine Heritage Policy Center. Meanwhile, Schneider, who is considered more moderate, has rented Snowe's constituent email list.

Rob Jesmer, chairman of the National Republican Senatorial Committee, said in a written statement that Pingree's withdrawal showed that Democrats had "privately anointed" King.

"The decision by national Democrats to throw Chellie Pingree and other proud Democratic leaders in Maine aside, in favor of an 'independent' who supported President Bush in 2000, makes clear they are more concerned with holding onto power in Washington, than trying to advance their own party's principles," Jesmer said.

smistler@sunjournal.com

This story has been clarified to note that Rick Bennett is a former board member of the Maine Heritage Policy Center.