With Chief Justice John Roberts’ unthinkable decision to uphold Obamacare yesterday, all focus now shifts to repeal for conservatives. In order to repeal Obamacare, two things must happen: Republicans must retake the White House, and they must retake the Senate.

Contrary to popular opinion, Republicans don’t need a 60-vote majority to ram through an Obamacare repeal – as Ken Klukowski pointed out yesterday, “The only way to stop Obamacare now is with a one-page repeal bill that must be passed by the House and Senate. Because it would reduce the deficit you can pass it with 51 votes as a reconciliation bill in the Senate; you don’t need 60 votes.”

Republicans currently have 47 seats in the Senate. They only have 10 Senate seats up for re-election, as opposed to Democrats’ 23. Essentially, Republicans need to shift three seats from the Democrats and hold their own in order to win repeal, since the VP is the tiebreaker – although that assumes homogenous Senate Republican support for repeal.

Republicans essentially have four vulnerable seats; Democrats have up to ten. The question is how the Obamacare decision will play into these races – if Obamacare is unpopular in these states, that will certainly cut in Republicans’ favor. One thing is clear: swing-state voters do not like Obamacare. First, the Republican toss-up races:

So the prediction for Republicans is that they will lose Maine, and hold the other three. At the worst, Republicans will lose two seats of these four.

Now for the Democrats. And this should have Republicans licking their lips:

The prediction: Republicans will pick up at least five seats from the Democrats. And with increased conservative excitement and turnout thanks to the fact that the Senate is the crucial battleground for Obamacare repeal, the numbers may be better than that.

So, if Republicans can hold two of their four vulnerable seats and take five from the Democrats, they’ll have 50 votes – and the prospective Romney vice president will be the tiebreaker. That will be a difficult task. Repeal of Obamacare will come down to the wire – and in these states, every call, every canvassing, every vote will count.

It’s up to these swing state Americans to decide whether we all move further down the path toward nationalization of health care. The opportunity is at hand to repeal Obamacare. It’s an opportunity we can’t afford to blow.