What House and Senate leaders don’t agree on, necessarily, is how to get the legislation done. Waxman and Rangel are more than happy to shove a bill down the throats of their Republican colleagues, if need be. That’s why the House forced Senate leaders to accept a provision in the budget that allows health care to pass by “reconciliation” — an arcane budgeting maneuver that would enable Senate Democrats to force through a bill with a simple majority, rather than with the 60 votes needed to forestall a filibuster. But in the Senate, Baucus remains determined to send to the floor a bill with bipartisan support; passing health care reform by reconciliation, he says, would make the new law unsustainable in the long term. This is why Baucus hasn’t yet committed to the idea of a public plan to compete with private insurers. It’s not that he particularly dislikes the policy or that he can’t find enough centrist Democrats who might vote for it. It’s more that Baucus fears the provision will drive away Republicans, making it far less likely that Democrats can pass a bill without resorting to reconciliation. During our conversation in his office, Baucus told me his main goal is to keep Senate Republicans at the negotiating table for as long as he can. “Everything is on the table,” Baucus told me more than once, which is the same theme he’s been hammering home to his Republican colleagues.

When I asked Baucus what he needed from the White House in order to help pass a viable health care plan, his answer, more or less, was nothing — as in, the most helpful thing they can do is butt out and let the Senate worry about the details. No doubt this has something to do with the traditional turf battles among the branches; Baucus has been a legislator now for 35 years, and he doesn’t need another Democratic president telling him how to do his job. But there is a more practical reason for his wariness, as well. So far, he has managed to keep the parties talking largely because neither Democrats nor Republicans have any clear idea of which specific provisions Obama will accept — and that’s exactly the way Baucus wants to keep it. If the president were to shed his reticence and set out his terms for a bill, Republicans would focus on their differences with Obama and would most likely end up abandoning the process, either because they wouldn’t believe a compromise was possible or because they would want to seize on any excuse to derail his agenda. “Right now, the president sort of keeps them guessing as to what he might be supportive of,” says John Breaux, the former Democratic senator who is now a corporate lobbyist. “I think that’s why you still see Republicans actually trying to work on it.”

As it happens, this arrangement — whereby Baucus negotiates the bill and Obama keeps his distance — is politically advantageous to the president too. During his campaign last year, Obama took at least two positions on health care that he may soon find hard to maintain. First, in the primaries, he differentiated his plan from Hillary Clinton’s by refusing to back an “individual mandate” — that is, the provision that would require every American to obtain insurance. Then, during the fall campaign, Obama criticized John McCain for proposing to tax employer-based health benefits. If he were to offer a detailed proposal of his own right now, Obama might have to walk out into the Rose Garden and reverse himself on one or both positions. But with Baucus urging him to leave the details to his committee, Obama can instead wait for a plan to emerge from the Senate and then, if need be, reluctantly change his mind in the interest of compromise. Thus he preserves the option of backing away from his previous anti-big-government stances, and he gets to appear statesmanlike and pragmatic in the process.

THE NETTLESOME THING about leaving the details of the health care plan to Congress, though, is that this Congress, like most every other Congress, doesn’t appear inclined to pay for much of anything. And it is this part of the health care debate — where to find the money — that seems most likely to derail the process. Most discussions of America’s health care woes begin with talk of the uninsured — some 46 million of them at last count. How much a new health care system will cost depends primarily on how close to universal coverage you really want to get. On the high end of the scale, insuring every American might well cost as much as $1.5 trillion over the next decade at a time when deficits are gobbling up a greater share of the nation’s income than at any time since World War II.

The White House has focused mostly on new efficiencies in health care, insisting that lowering the costs of medical care could easily save $2 trillion in public money over the next decade. A coalition of providers, drug makers and insurance companies — no doubt looking for the best possible deal in health care legislation — helpfully vowed in a White House photo-op last month to institute changes that would lead to such savings, but their promise was maddeningly vague and utterly unenforceable (and in any event, the industry groups almost immediately distanced themselves from it). Short of realizing these projected savings, there are only so many ways to pay for health care — and, not surprisingly, congressmen and senators aren’t exactly lining up to embrace them. One way, as McCain proposed, is to rescind the tax exemption for some workers who receive health care benefits from their employers; Baucus is open to at least capping the exemption, but labor unions are adamantly opposed, and Rangel has publicly renounced it (though he and other House Democrats appear to be re-evaluating that stance). Another way is to slap new taxes on some of the products that cause health problems in the first place, like soft drinks, but industry lobbyists are already spending satchels of cash to head that off. Congress can always choose to slash Medicare benefits or the payments that doctors receive, but that idea generates about as much enthusiasm as you might find for putting George W. Bush’s face on the $5 bill.

In a larger sense, this may be the nagging flaw in Obama’s notion of the Congressional presidency, this strategy that leaves the lawmaking to Congress, even as it enables him to claim credit for one legislative success after another. Professional legislators can be great at devising complex language and finding creative ways to get a deal. What they are not especially good at — at least not in the current era — is making the difficult decisions that governing responsibly often requires. Left to their own devices, legislators rarely seem to ask the voters to sacrifice anything by way of taxes or entitlements or services, if only because voters don’t find the entreaties of legislators all that persuasive. And so, absent his own engagement, Obama’s vow to reverse our “collective failure to make hard choices,” as he put it in his inaugural address, may well be pushed aside for another day.

At critical times in his young political life, and several times already in his presidency, Obama has fallen back on his gift for explanation and oratory to try to change the dynamic of a national debate. He did it on race relations, delivering a historic and bracingly candid speech in Philadelphia during the Democratic primaries. On two consecutive days last month, he undertook to lay out his thinking on national security and civil liberties in twin speeches at the National Archives and the Naval Academy. In a recent speech at Georgetown University, he tried to tell the larger story of the nation’s economic crisis and his response to it, riffing on the Biblical image of a house built on shifting sand. It seems likely that Obama, who has to this point focused on a sophisticated legislative strategy for achieving health care reform, will at some point soon have to take his case to the public instead — this time asking Americans not just to support an ambitious expansion of government but to accept the sacrifices necessary to do it. Only a president will make that case, and only a president can.