Why is Rep. Barney Frank retiring? (VIDEO)

Rep. Barney Frank isn’t going to run for reelection. The Massachusetts Democrat with the acidic wit is calling it quits after 16 terms of sparring with Republicans, reporters, various administration officials, witnesses at hearings who displeased him, and even constituents who disagreed with him in public.

“Barney Frank will not seek reelection. Congress just got a little bit dumber, and a whole lot duller,” tweeted liberal Washington Post columnist Ezra Klein when he heard the news.

Why is he calling it quits now? He’s an icon of the left, the inheritor of the seat of another icon on the left, the Rev. Robert Drinan. He could raise all the money he wants. He’s one of the few openly gay elected national officials in US history. He’d probably gain extra votes in 2012 due to President Obama appearing on the blue Bay State ticket.

Well, all that is true, but we can think of a number of reasons that Representative Frank might want to let somebody else run in the Massachusetts Fourth District.

He's not getting younger. Hard as it is to believe for those of us who remember a rumpled youngish guy knocking off Republican Margaret Heckler in an epic 1982 race caused by redistricting, Frank is now in his early 70s. If he wants a second career – as a reporter, an administration official, or a Washington lobby ... oops, Washington consultant – now is the time to make the change.

Democrats might not win back the House. Frank rose to the height of Washington power as chairman of the House Committee on Financial Services from 2007 to 2011. He helped push through financial reform legislation and championed the giant quasi-government mortgage giants Fannie Mae and Freddie Mac – actions that have made him a GOP target. But Republicans took control of the chamber in the 2010 midterms, and they may well maintain their grip on the speakership after 2012. Frank’s retirement may indicate that top House Democrats don’t think that much of their chances in the upcoming vote.

He might have lost. Most important, Frank would not be running in the same district in 2012, geographically speaking. A new state redistricting map made necessary by relatively slow population growth shoved some conservative towns into Frank’s Fourth District, while depriving it of reliably Democratic New Bedford. Frank could have still counted on his liberal base of Newton. But he’d have faced another challenge from former Marine and presumptive GOP candidate Sean Bielat, who gave Frank a tough challenge in 2010. Why bother? Perhaps that was Frank’s attitude.

Frank may not be the only longtime lawmaker in such a predicament. The low regard in which voters currently hold Congress could affect the reelection prospects of many current legislators, predicts political analyst Charlie Cook.

“Voters hardly seem inclined to reward either party,” Mr. Cook wrote earlier this month. “Instead, we may well see many incumbents – those wearing blue Democratic jerseys as well as those wearing red Republican ones – thrown out the window, not so much because of their uniforms but because of their proximity to windows.”