West Virginia Senator Robert Byrd died Monday at 92. He was an outspoken proponent of legislative power and served in the Senate for 51 years, longer than anyone else in American history. (For more on his legacy, check out Adam Clymer's terrific obituary in the New York Times). His death comes as Democrats seek to pass financial regulatory reform and are short on votes. His successor will be chosen by West Virginia's Democratic Governor Joe Manchin, but the timing of that appointment is in question. Here's the political fallout of Byrd's death:

• Puts Wall Street Reform In Peril, writes John Bresnahan at Politico: "Massachusetts Sen. Scott Brown, one of four Republicans who voted for the original bill, has said he might vote against the [conference] version because it adds a $19 billion bank tax. Should Brown vote no and with the loss of Senator Byrd, it would leave the bill one vote shy of the 60 needed to close debate and move to final passage."

• Democrats Would Have to Pick Up Votes from One of These Republicans, writes Meena Thiruvengadam and Damian Paletta at The WSJ: "Four Republicans, Scott Brown of Massachusetts, Olympia Snowe of Maine, Susan Collins of Maine, and Charles Grassley of Iowa, voted for the bill in May, and Democrats would need the four to back it, in order to get exactly 60 votes."

• A Democratic Appointee Could Stay Until 2012, writes Marc Ambinder at The Atlantic: "Democratic Gov.  Joe Manchin will appoint Byrd's successor. Given the time frame -- outside two and a half years before Byrd's term expired -- a special election will be held in November. Democratic sources say they think that Nick Casey, the state Democratic party chair, had been quietly tapped (and approved) to be his fill-in/successor should a vacancy occur.  Sen. Harry Reid and others have been consulted on this eventuality. The only ambiguity here is when Manchin officially declares a 'vacancy' in the seat; if he does so after July 3 somehow, then his hand-chosen replacement could serve through 2012. If not, the successor serves a few months, and Republicans get the chance to pick another Senate race in 2010."

• Democrats Have Delayed Vacancy Announcements Before, notes Jim Geraghty at National Review: "In New York, David Paterson waited months before declaring Eric Massa’s House seat vacant. The idea of Manchin waiting a week to recognize the vacancy is not unthinkable."

• However, It's in Governor Manchin's Interest to Announce the Vacancy Now, writes Steve Kornacki at Salon:

Byrd's seat is probably Manchin's only way of retaining his political viability and furthering those national aspirations. The assumption, then, is that Manchin would simply appoint a placeholder to the seat, someone to keep it warm until he can run for it himself.

Manchin could potentially get to decide whether he wants to run this fall, or if he'd rather wait until 2012. Even though this fall figures to be rough for Democrats, it's probably a better time for Manchin to run. He's plenty popular now and, thanks to his cultural conservatism and staunch defense of the state's coal industry, he's separated himself enough from Barack Obama and the national Democratic label that he'd probably be fine. And his presence in a special election this fall would probably scare off the strongest potential Republican, Rep. Shelley Moore Capito. But if Manchin has to wait two years to run, circumstances could change.

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John Hudson