The problem is in the House, not the Senate.

The Democrats' strategy for passing health care reform is taking shape. The House will pass the Senate bill. Then the House will pass (through the budget reconciliation process, under which legislation can't be filibustered) a bill making certain changes to the Senate bill to bring it in line with President Obama's Feb. 22 proposal. For a while it was unclear whether the House or Senate would pass reconciliation first, but House Majority Leader Steny Hoyer, D-Md., cleared the matter up in a Feb. 28 appearance on CBS News'Face the Nation. "The House will have to move first on some sort of corrections or reconciliation bill," Hoyer said.

But does the House have the votes?

Until now, most attention has been focused on the Senate and whether there's sufficient support to bypass the threat of filibuster through reconciliation. The answer is probably yes. According to a whip count of the Senate's 59-person majority by Chris Bowers of Open Left, 41 Senate Democrats support using reconciliation; an additional six say they may support it; and 11 are undecided. Only one (Sen. Blanche Lincoln of Arkansas) affirmatively opposes it. Of the 17 Democrats in the maybe/undecided column, Majority Leader Harry Reid, D-Nev., need only pick up nine. That's eminently doable because it's become increasingly obvious that reconciliation isn't the exotic legislative technique Republicans make it out to be.

The problem lies in the House. That may seem counterintuitive, given that the House passed a bill on Nov. 7 that was more liberal than the Senate bill. Asked to choose between the more conservative Senate bill (with the flat-out unacceptable parts altered in a separate reconciliation bill) and no health reform at all, why wouldn't the House choose the Senate bill?

The answer begins with the fact that since Nov. 7, when the bill passed the House quite narrowly, 220-215, House Speaker Nancy Pelosi has lost three votes. John Murtha, D-Pa., died; Robert Wexler, D-Fla., resigned to become president of the Center for Middle East Peace and Economic Cooperation; and Neil Abercrombie, D-Hawaii, resigned to run for governor. Balanced against these yeas is one nay, Nathan Deal, R-Ga., who just resigned effective March 8 to run for governor. That narrows health reform's victory margin from five votes to three (217-214). If President Obama is serious about acting within six weeks, then the final House vote will come before special elections to replace Wexler (April 13), Murtha (May 18), and Abercrombie (May 22), and probably before any elections to replace Deal, too (though no date has yet been set). Even if the Democrats wait till late May, there's a pretty good chance the special elections will keep the victory margin at three votes (219-216), because Murtha's district tilts slightly Republican; McCain eked out a narrow victory there in 2008. (The other seats are unlikely to change party, judging from the Cook Political Report's partisan voting index.)

We will assume, then, that Pelosi starts with a victory margin of three.

Take away from that three Rep. Bart Stupak, D-Mich, and Joseph Cao, R-La. Stupak is the author of a House amendment on abortion that has the imprimatur of the U.S. Conference of Catholic Bishops. Both Stupak and the bishops say they won't support the Senate bill's language on abortion. Neither will Cao, the sole House Republican to vote for health reform on the first go-round. Why not resolve the dispute by putting the Stupak amendment into the reconciliation bill? Because Senate rules won't allow it. To be included in a reconciliation bill, a measure must have some impact on the federal budget. If Stupak and the bishops were truthful in their claim that the Stupak amendment merely preserved the Hyde amendment's existing ban on federal funding for abortions, then the Stupak amendment would indeed affect the federal budget by stripping from the Senate bill its supposedly noxious federal funding for abortions. But the Senate bill doesn't fund abortions. According to Nick Baumann of Mother Jones, the Congressional Budget Office affirmed before the Senate vote that its abortion language would have no budgetary effect. Therefore, a Reid spokesman told Baumann, reconciliation can't be used to restore the Stupak amendment to health reform. ("No one thinks you can change the abortion language under reconciliation," George Will said Feb. 28 on ABC News' This Week. Inadvertently, this pro-life commentator was calling the U.S. Conference of Catholic Bishops a bunch of liars. He's right!)

Take away Stupak and Cao and the House health-reform bill lacks a majority if the vote is held before the special elections (215-216). It also lacks a majority if the vote is held after the special elections and Murtha's seat goes Republican (217-218). Health reform retains a one-vote margin of victory only if Murtha's seat stays Democratic (218-217). But before you whip out your checkbook and give all your money to Pennsylvania's Democratic party, read on, because health reform's troubles don't end here.

Stupak and Cao aren't the only pro-lifers in the House who will change their vote from yea to nay if health reform doesn't include the Stupak amendment. Stupak says he counts 15 to 20 Democrats who will do so. (Previously, he said there were 40.) Most calculate the Stupak bloc at about one dozen. A Feb. 24 memo by House Minority Whip Eric Cantor, R-Va., identifies, in addition to Stupak and Cao, 10 House Democrats who may bolt over abortion. In January Nate Silver of the Web site FiveThirtyEight.com calculated only 10 likely Stupak bloc bolters, but six of Silver's 10 (including three of those he deemed most likely) weren't on Cantor's list at all. So lets call it 12.

Take away a dozen votes and the House health-reform bill fails by a 21-vote margin before the special elections (205-226). If the vote is after the special elections and Murtha's seat goes Republican, it also fails by 21 votes (207-228). * If Murtha's seat stays Democratic, it fails by 19 votes (208-227).