WASHINGTON -- Congressional Democrats expressed a rare touch of nonchalance Wednesday as House Republicans voted to repeal last year's health care overhaul, since the repeal has little chance of passing the Senate. Behind the scenes, however, fears are mounting over what appears to be a more serious threat.

Democratic lawmakers tell The Huffington Post that they increasingly expect Republicans to try and freeze funding for the health care law. Such an attempt would face the same institutional hurdles as a straight repeal vote: a non-compliant Senate and a president wielding a veto pen. But whereas the repeal bill's death would mean -- in practical political terms -- absolutely nothing, the inability to pass an appropriations bill could have far-reaching effects.

"They are potentially setting up a situation where they will bring government, all of government, to a screeching halt," Rep. Debbie Wasserman Schultz (D-Fla.) said Wednesday. "Not because of the debt ceiling. This is beyond the debt ceiling ... If they think they are going to have the end game of their appropriations bills be that they drive health care reform into an early grave ... they are literally setting up a full stop for almost everything we will possibly do this year."

"I am real concerned," Rep. Charlie Gonzalez (D-Texas) said. "We do operate on yearly budgets that could exact great harm if they are dedicated to that proposition. You still have to work with the Senate. So what happens when you reach that kind of impasse? We have this gridlock ... There is no doubt in my mind that the Republican leadership ... has already charted a course. They are very disciplined and very good at what they do."

"This is only the beginning," Rep. John Dingell (D-Mich.) said. "I'm also fearful that they are going to try and eviscerate the legislation by denying it funding [and] by harassing the administration."

"I'm very concerned," Rep. Peter Welch (D-Vt.) said. "There are a lot of things that need funding in order to be implemented ... Here is the point: these guys are serious. Give them credit. They said what they were going to do with repeal and now they are doing it ... There is no ambiguity here and anyone who doesn't see [defunding] as a deadly serious effort on the part of GOP leadership is naive."

Republican aides were coy when asked for a response to such concerns. To this point, much of the party's emphasis has been placed on the just-completed repeal vote -- which Senate Minority Leader Mitch McConnell (R-Ky.) has pledged to duplicate in the upper chamber -- and on proposed hearings that would examine aspects of the health care law.

But defunding the legislation has always been considered a far more plausible option than repealing it. The Affordable Care Act requires funds not just for implementation, but also to pay the implementers. And while much of the money has either been sent to the states or set aside for federal agencies, there are enough vagaries in the appropriations process that could cause major headaches for reform proponents.

Ask congressional aides and health care experts what provisions of the law are most likely to succumb to a defunding campaign and you get a variety of answers. Tim Jost, a law professor at Washington and Lee University, said there are four distinct funding subgroups.

Provisions like Medicaid expansion and premium tax credits, which the law has going into effect only in 2014, "are effectively mandatory spending," Jost said, meaning that "unless the law is changed, the money will be available. It doesn't need to be appropriated on an annual basis."

For elements of the bill like community health centers, the money has been both authorized and appropriated. In other words: the dollars are out the door.

In cases where the money was authorized but not appropriated, like the wellness initiatives and training for primary care physicians, such provisions "will ultimately have to be set aside in future budgets."

Finally, there is the money for funding the agencies themselves, which is part of the annual appropriations process.

"I don't think that [defunding] is a serious threat," Jost concluded. "But it is the strongest hand the Republicans hold."

Among the four groups of reform provisions that Jost pinpointed, the last has congressional Democrats most nervous. With respect to components that still need to be funded (the third subsection) there is a growing expectation that Republicans won't touch those programs. "The things that require appropriations and aren't fully funded in the health care bill have bipartisan support," a senior Democratic aide said. "So if they want to withhold funding from the [law] they would get push back."

It's if Republicans start chipping away or restricting funds for the agencies "that would be problematic," the aide added.

Len Nichols, an expert on health care budgets at George Mason University, also said funding for the fourth section was the most "stoppable." In essence, Republicans could author legislative language that restricted Department of Health and Human Services Secretary Kathleen Sebelius from spending a single cent on Medicare payment reform. "Then it comes down to, logically, a debate over why you are against it," Nichols said. "Do [Republicans] need a symbol so badly that they will cut off their nose to spite their face?"

There is some disagreement as to whether this gambit would be all that effective. HHS, like other agencies, has some latitude to move around its own budget as it sees fit.

But for all the fretting over a forthcoming funding battle, Democratic leadership seems relatively optimistic when asked Nichols' question. GOP lawmakers may view health care funding as the best avenue towards dismantling the legislation, but the public relations dynamics aren't in their favor. Though the Affordable Care Act may have mixed popularity among the public at large, its individual provisions are remarkably well liked by the country. And if Republicans manage to freeze agency funding, Democrats would have a lot of material with which to tar them.

"Hopefully that will not happen," Minority Leader Nancy Pelosi told a gathering of new media reporters and political bloggers on Wednesday. "But we will just see how irresponsible they are ... they say they are going to hold back funding on everything. I don't know what they get at by that. But I think we would have to discreetly respond. This is what withholding funding ... would mean to you."

