Freshman House Democrat Eric Massa has announced he will not seek reelection. The announcement comes just over a year into his first term, and rumors about the reason for his retirement have focused on Massa's health -- he suffers from lymphoma -- and salacious sexual allegations. Whatever the reason, the retirement could carry bigger significance for a Democratic Party beleaguered by recent retirements and looking ahead to a difficult 2010 election season.

• Red Districts More Hostile to Dems  The Washington Post's Chris Cillizza notices a trend in districts won by McCain's 2008 presidential run. "Massa is the seventh House Democrat leaving a seat that Sen. John McCain (R-Ariz.) won in 2008. That means that 43 percent of the Democratic retirements in the House so far in this election have come in McCain districts. It also means that 14 percent of the 49 Democratic members who hold McCain districts are retiring this fall." If the trend continues, Democrats could lose their majority in the House. "Conventional wisdom has suggested that if Democrats have to defend 10 or more seats either won by McCain or narrowly carried by Obama that their majority status might be legitimately in danger."

• Dems' Discipline Problem  The American Prospect's Tim Fernholz warns that between Massa and just-censured Democratic Congressman Charlie Rangel, Dems need to work on their image. "Their failure to control their members' shenanigans is overshadowing their last-ditch effort to do one of the few big moves that would improve their chances. That said, I don't think either of these stories seriously jeopardizes the health care bill's chances of passage; the structural incentives are there for the reconciliation fix plan to work."

• GOP Could Pick Up His Seat  Roll Call's Paul Singer and Greg Giroux report that Republicans already had their eyes on Massa's GOP-"leaning" upstate New York seat, and could win it in November. "The GOP had been targeting Massa for defeat in November, and the race to succeed him will likely be competitive. He is the 15th Democrat to announce plans to leave the House at the end of this year."

• Massa's Hard-Left Swing  The New York Times reports on his unique political journey. "Formerly a Republican, Mr. Massa campaigned in 2006 on his opposition to the Iraq war, which precipitated his switch to the Democratic Party. Mr. Massa has been a proponent of a single-payer health care system and was one of 39 House Democrats to vote against health care legislation, saying it did not do enough to rein in costs." Could the Republicans-turned-liberal-Democrats of the American political scene be a dying breed?

• New York Dems Really Struggling  The Atlantic's Chris Good reminds us that Massa is far from the only troubled Democrat in the deep-blue state:

More bad news for New York Democrats after what has already been a bad few days: on Friday, Gov. David Paterson announced he won't seek reelection ... and today Rep. Charlie Rangel, the senior Democrat from Harlem, announced he would step aside as chairman of the powerful House Ways and Means Committee after the House ethics panel found Friday that he had improperly taken gifts in the form of trips to the Caribbean.

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