In order to take control of the US Senate, Republicans have to win six seats in the midterm elections.  Or is it five? That depends on one of the two Senators unaffiliated with either major party. Bernie Sanders, a professed socialist, may run for the Democratic Party presidential nomination in 2016, so a Sanders flip is unlikely in the extreme. But what about Maine’s Angus King? He caucuses with Democrats now, but he’s, er … mulling his options after opposing the Democratic pay-equity ploy:

Sen. Angus King (I-Maine), who caucuses with the Democrats, will decide after the midterm elections whether to switch sides and join the Republicans.

He is leaving open the possibility of aligning himself with the GOP if control of the upper chamber changes hands.

“I’ll make my decision at the time based on what I think is best for Maine,” King told The Hill Wednesday after voting with Republicans to block the Paycheck Fairness Act, a measure at the center for the 2014 Democratic campaign agenda.

King’s remarks are a clear indication that congressional leaders on both sides of the aisle will have to woo the 70-year-old senator in order to recruit him to their side.

That would be quite a journey for King, who just this week offered to waterboard former VP Dick Cheney after the latter defended the Bush-era interrogation techniques. King has been firmly in Harry Reid’s camp since replacing Olympia Snowe fifteen months ago. He explained that to Maine voters (who had rejected both Republican and Democratic options in the race) on purely practical grounds. Without an affiliation to a caucus, King would have had no committee assignments at all, and it’s better to caucus with the majority to get more impact.

In other words, don’t expect King to vote in lockstep with the GOP if he switches. And it’s not entirely clear that Senate Republicans will want him unless they absolutely need him. King backs ObamaCare, for instance, and voted in favor of Reid’s nuclear option on the filibuster last year. He also wants federal legislation to limit firearms magazines to 10 rounds, but does not support an assault-weapons ban. King filed an amicus brief with the Supreme Court arguing to strike down the Defense of Marriage Act. Govtrack’s analysis of his voting record puts him on the moderate side of the Democratic caucus, about equivalent with Mark Pryor and Tim Kaine, but slightly more liberal than the most liberal Republican — his colleague Susan Collins.

Don’t expect the GOP to woo him much, in other words, unless they really need him — and they will only really need him if they pick up exactly five seats. Six and they don’t need him to take control; four and he can’t help anyway, unless they can convince Joe Manchin to flip, and they might try him first at five, too. Manchin’s voting record is closer to the GOP than King’s, and the trend in his home state might make him more reliable, too. King will flip to the GOP if they win a majority to any extent, thanks the pragmatism that has him in Reid’s caucus now.