Senator Evan Bayh's shocking retirement has made the impossible seem possible: Democrats could go from holding a 60-vote supermajority to losing the Senate majority completely. This prospect still seems remote to many analysts, since it would require Republicans to win every Democratic-held seat at play, while losing none of their own. But still, what are the odds?

• Possible, but a Long Shot  Chris Cillizza at The Washington Post says the loss has "considerable" implications on the national stage, and cites electoral guru Charlie Cook's placement of 10 Democratic seats in his "most competitive categories"--in other words, "if Republicans run the table and don't lose any of their own vulnerable seats they could take back the Senate." Yet Cillizza isn't betting any money this will happen. "With so little room for error, however, it's still a long shot for Republicans to take over the upper chamber. To expand their chances, the GOP must continue to expand the playing field, with Senate races in Wisconsin and Washington State the most likely possibilities."

• Entirely Possible  David Catanese of Politico puts a bolder spin on it, saying the Dems' majority is now "within striking distance." He outlines five ways this could happen. Here are three of the possibilities: "The situation in Arkansas continues to deteriorate ... Romanoff roughs up Bennet in Colorado ... Third time's a charm for Rossi in Washington."

• Bet Against It  Nate Silver of FiveThirtyEight runs the numbers, and places his bets against a Republican rout of the Democrats. He says it's quite possible to see a scenario in which the Republicans win. The trick, however, is that Republicans can't lose any of their seats in the meantime. "This is the factor that the market may not be properly accounting for. The Democrats are competitive right now in Missouri, Ohio, New Hampshire, and Kentucky, could become that way in North Carolina and possibly Florida, and there's an outside chance they could get a wild card of their own like Arizona. In most of these races, you either have a Republican (in an anti-establishment year) who is more a part of the establishment than his opponent, primary dynamics that could lead to the selection of an inexperienced or too-conservative candidate, or both."

• Not Only Possible--Lieberman Could Tip the Scales  Sean Trende at RealClearPolitics writes that Bayh "upsets a year's worth of comfortable predictions" that Republicans didn't have a chance to take back the Senate. Now he says confidently that the Senate Bottom is "likely to be in play come election day in November." Spelling out a perfect GOP performance, he then sees how they could even get to 51 votes: "If the GOP does manage to get to 50 seats, then another variable enters the picture: Joe Lieberman. Would Lieberman caucus with the Republicans in order to deny the Democrats a Senate majority?"
  
  

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