Filing closed Monday in Maine, where an open House seat is attracting big attention from a number of prominent Democrats. The state's First District, based around the state capitol in Augusta and the largest city, Portland, came open after Democratic Rep. Tom Allen made his bid for Senate official, and the resulting race to file for office was nothing short of a free-for-all.

Of the six candidates to file, former Common Cause President Chellie Pingree is the early front-runner, with polls from her campaign showing her well ahead of the other competitors. One recent survey, from prominent pollster Celinda Lake, shows Pingree leading the field with 38%, while no other candidate cracks double digits.

But Pingree won't have an easy ride in the state's June 10 primary. The former State Senate President and 2002 Senate nominee will face two other ex-Senate leaders, Mike Brennan, who served as majority leader, and Mark Lawrence, who served as President and ran for Senate against Republican Olympia Snowe in 2000. Current State Senator Ethan Strimling is also in the contest, as are physician Steve Meister and attorney Adam Cote, both of whom served in Iraq.

The primary will not be cheap, by any means. Pingree had already raised nearly $800,000 through the end of 2007 and spent $340,000. Lawrence, Strimling and Cote had all raised more than $300,000 as well. To win, Democrats will need to convince the district's large population of liberals to back their cause. In that pursuit, Pingree trekked to Washington on Monday to join about a dozen other challengers from around the country who back a withdrawal from Iraq and allowing lawsuits against telecom companies who cooperated with the government in aiding eavesdropping.

The state's other hot race will be the Senate contest, where Allen faces incumbent Republican Susan Collins. In a state that votes heavily Democratic in presidential contests, Allen is the Democrats' best possible candidate, though two polls in the Fall showed Collins with wide leads.

Only one Republican filed against Second District Rep. Michael Michaud, further confirming that what was once a battleground district -- he won his first race, in 2002, by a 52%-48% margin -- is now safely in the Democrat's hands.