Four reasons why the prickly Connecticut senator may not remain in health reform's "yes" column.

Sen. Joe Lieberman, after threatening to filibuster health reform over the public option and later over the Medicare buy-in, has been bought off. On Dec. 15, after Senate Majority Leader Harry Reid removed the Medicare buy-in and the public option from the bill, Lieberman told reporters, "I'm going to be in a position where I can say what I've wanted to say all along: that I'm ready to vote for health care reform." He reportedly said the same thing at a White House meeting that day. Lieberman's statements shifted attention to Sen. Ben Nelson, D-Neb., now widely believed to be the last holdout in the Democrats' 60-person caucus. (Lieberman of Connecticut and Sen. Bernie Sanders of Vermont, though both independents, caucus with the Democrats.) "Nelson,"writes Janet Hook in the Los Angeles Times, "is the only Democrat that leaders are really worried they could lose."

If Nelson really is the caucus's last holdout—the only remaining obstacle to a filibuster-proof majority—then hallelujah. But I harbor lingering doubts that Lieberman will remain in the "yes" column. Here's why.

1. No CLASS. On Dec. 13, Lieberman appeared on CBS News' Face the Nation. Let's go to the transcript.

Lieberman: [T]here's a good basic bill in here and—and the part of it can be supported by 60 senators, including some Republicans, but we've got to stop adding to the bill. We've got to start subtracting some controversial things. I think the only way to get this done before Christmas is to bring in some Republicans who are open-minded on this like [Sen.] Olympia Snowe. I'll tell you if—

Bob Schieffer: Well, what do you have to do to do that?

Lieberman: You've got to take out the Medicare buy-in. You got to forget about the public option. You probably have to take out the [Community Living Assistance Services and Support] Act, which was a whole new entitlement program that will in—in future years put us further into deficit. And you got to adopt some of the cost containment provisions that will strengthen cost containment that all of us favor. If you did that, you'd have an enormous accomplishment.

[…]

Schieffer: Give me that list of things that have to be taken out to pass it.

Lieberman: Well, from my point of view, no public option, no Medicare buy-in, CLASS Act which will add debt to our future. Don't take much more than that ….

To review: Public option? Out. Medicare buy-in? Out. CLASS Act? Er, whoops. As far as anyone knows, that's still in.

The CLASS Act is a proposed new voluntary government insurance program for nursing-home care when you get old and long-term care if you become disabled. By law it must pay for itself, but the Congressional Budget Office says the Senate version would start running a deficit in 20 years; the Centers for Medicare and Medicaid Services puts it at 16. Twenty or even 16 years is plenty of time to fix CLASS's solvency problem. But if Lieberman decides to make an issue of it, these estimates give him the ammo to do it. Indeed, arguing that CLASS would represent an unfunded liability would make more actual sense than arguing the same about a public option or Medicare buy-in, as Lieberman has already done. CBO scored the public option as a (slight) deficit-reducer, and Lieberman spoke before CBO had a chance to offer any budget estimate regarding the Medicare buy-in.

Where does he stand on CLASS? With a slippery fellow like Lieberman, one hesitates to say. But as of 12:35 p.m. on Dec. 17, he stood here (according to an e-mail from a Lieberman aide who asked not to be identified): "While the senator has significant concerns with the CLASS Act, it is not a 'deal breaker' in the bill." That's mildly reassuring, but it leaves Lieberman plenty of room to combine CLASS with one or two other concerns to justify last-minute opposition.

2. No finance. Before health reform was a Reid bill, it was a Baucus bill. The bill reported out of the Senate finance committee chaired by Sen. Max Baucus, D-Mont., contained no public option, no Medicare buy-in, and no CLASS Act. Yet after it passed, when talk radio host Don Imus asked Lieberman whether he'd vote for it, Lieberman said, "No, not the way it is now." Why not? "I'm afraid that in the end the Baucus bill is actually going to raise the price of insurance for most of the people in the country." Lieberman was parroting a just-released insurance industry study of little value, but when CBO looked at this question a few months later in more nuanced and objective fashion, it, too, found that health reform would tend to increase health insurance premiums (though not nearly so much as the industry study said, and when new government subsidies are factored in, the cost of those premiums would be reduced below current levels for a majority of those buying health insurance on the new exchanges). I've argued elsewhere that while there are many reasons to favor health reform, cost control is no longer one of them. If Lieberman wants to make a stink about health reform increasing the price of health insurance, the facts won't stand in his way.

Lieberman also complained in the Imus interview that under the Baucus bill, taxes would go up to pay for the uninsured. That's indisputably true (and, I think, indisputably necessary). But if Lieberman still wants to raise a ruckus about that, he can.

I asked the Lieberman aide whether Lieberman's views on the Baucus bill had changed. Here is his reply:

One of Sen. Lieberman's concerns with the Finance Committee bill was that it would increase premiums for those currently insured more than those premiums would otherwise increase under current law. At the time the finance committee approved the bill, there had been no comprehensive analysis by CBO or [the joint committee on taxation] on how the bill would affect those premiums.

Additionally, Sen. Lieberman was not convinced that the finance committee bill would do enough to lower health care costs. That is why Sen. Lieberman introduced and cosponsored amendments to Sen. Reid's [bill] that will lower costs over the long term. Just today, Sen. Lieberman will join Sens. Rockefeller and Whitehouse on the Senate floor to discuss an amendment to strengthen the newly created Independent Medicare Advisory Board in Sen. Reid's bill. The amendment could potentially double the $23 billion in savings it currently achieves.

This suggests but does not flat-out assert that the CBO analysis, which showed the premium increase resulting from health reform to be far less drastic than the industry predicted, quieted Lieberman's concern on this point. I hope that's the case, but I'm not putting it in the bank. Lieberman's proposed amendment (text, summary, press release) to put teeth back into the budget-cutting Independent Medical Advisory Board, which Baucus and Reid quietly emasculated to buy off the hospital lobby, is indeed constructive and useful. But if it passes, Lieberman will have no strategic reason to continue to encourage Democrats to believe they've got his vote, and if it fails, that may become his reason to withhold it.

I also asked Lieberman's aide about the senator's complaint to Imus that subsidizing new health insurance policies would necessitate a tax increase. He responded, "Sen. Lieberman has always insisted that the legislation must be paid for." I interpret that to mean that Lieberman, regardless of what he did or didn't say to Imus (I've only seen a paraphrase  whose accuracy the aide neither confirmed nor denied) is not currently opposed to paying for health reform with a tax increase.