Chellie Pingree, the president of Common Cause, announced Tuesday that she will leave the government watchdog organization in February to explore a Congressional bid in her home state of Maine.

Pingree, a former state Senate Majority Leader, did not say whether she is looking to run for the House or the Senate. She unsuccessfully ran as the Democratic nominee in 2002 against Sen. Susan Collins (R), losing by 16 points.

Collins is up for a third term in 2008, and Rep. Tom Allen (D-Maine) is openly contemplating running against her. Pingree presumably would consider running for Allen’s open 1st district seat if the Congressman makes the Senate race, but she might also consider running for Senate, especially if Allen takes a pass.

Although national Democrats were optimistic about Pingree’s prospects against Collins initially, the race never became as competitive as they had hoped. With Maine trending ever more Democratic, however, national party leaders believe Collins is vulnerable this time.

Pingree already has spoken to EMILY’s List, the Democratic fundraising powerhouse that supported her Senate bid, about her desire to run for a Congressional office in 2008.

Although the group has not offered a formal endorsement, “we think she’d be a wonderful representative for Maine,” said Ramona Oliver, the EMILY’s List communications director.

If Allen runs for Senate, Pingree may not be the only Democrat seeking to replace him. Former state Senate Majority Leader Michael Brennan (D) already has created an exploratory committee to raise money for a possible House bid.

After spending more than $3.8 million on her losing Senate race, Pingree became president of Common Cause in March 2003. She is credited with expanding the group’s membership and spearheading efforts to limit the influence of money in state and local politics.

But Pingree was not always in sync with the leaders of other national government and campaign reform groups, in part because she never entirely lost her partisan veneer. Even after taking the helm of Common Cause, she appeared at Democratic events in Washington, D.C., and in Maine, where her daughter, Hannah Pingree, is now the state House Majority Leader.

Both Fred Wertheimer, president of Democracy 21 and a former Common Cause president, and Trevor Potter, president of the Campaign Legal Center, declined to comment about Pingree’s tenure Tuesday.

In a statement, Pingree appeared to indirectly address her critics, invoking the name of the group’s late founder in the process.

“Common Cause is one of the oldest and largest organizations dedicated to lobbying on behalf of the public interest, and I have been honored to lead it at a time when the public’s voice needs to be heard more than ever,” she said. “I leave with the confidence of knowing that Common Cause founder John Gardner had great reverence for the work of politicians and believed in the responsibility of those who were called to public service to step forward to do the work that must be done.”

Pingree’s last official day at Common Cause will be Feb. 10, which coincides with a meeting of the group’s national governing board. Jon Goldin-DuBois, the executive director, will assume Pingree’s duties until a permanent replacement is named.

Matthew Murray contributed to this report.