One of the most elusive concepts in politics is the notion of a mandate. Presidents love to claim them to bulldoze opposition (“the American people elected me to do this!”), but they can evaporate with astonishing speed, most famously in the case of the backlash against Franklin D. Roosevelt’s “Court-packing” plan after FDR had won the most sweeping electoral endorsement for any party in a presidential election year since the dawn of the modern two-party system.

If there’s one essential characteristic of a mandate, it’s that the public support behind the president is solid because people know what it is they’re supporting. That’s how conservative presidents like Reagan and George W. Bush got mandates to cut taxes: they ran on a clearly articulated plan, everyone who cared to follow the race knew what the plan involved, and public support didn’t change dramatically once they got into office and their opponents started hitting back with the same arguments they’d used against the tax cuts during the campaign. A corollary is that when Members of Congress voted for the tax cuts, they could do so knowing that the arguments on both sides had been fully ventilated to the public, and the voters wouldn’t turn against them quickly for supporting the cuts.

Barack Obama is now pressing forward on health care on the theory that he was elected on a platform of doing something about “health care reform,” and therefore he has a mandate. Bill Clinton thought the same thing; so did George W. Bush after winning not one but two elections while promising Social Security reform. One can argue about their assumptions (that both Obama and Clinton won because of the economy, and Bush in 2004 because of war, social issues and the economy), and of course it remains too early to predict whether Obama will succeed in getting a health care bill to his desk. But of this much we can be certain: even if he does, his legislative strategy is designed to ensure that the bill is passed without the controversial details being sold to the voters. And if Congressional Democrats follow Obama’s lead, they may find next fall that they can’t hide behind any sort of mandate to justify their votes.

From watching him approach the votes on the stimulus and cap-and-trade proposals and now health care, we have a pretty clear picture of Obama’s modus operandi:

Step One: Lay out very general principles and trumpet the absolute urgency of immediate action on those principles. Obama is in favor of “health care reform.” He wants to lower costs and insure more people. A high level of generality. There was more flesh on the bones of his campaign proposals, but not nearly at the level of covering all the bases, and in any event Obama has not even tried to insist that legislation be crafted around his campaign proposal. Yet he has insisted that even if he can’t say what exactly is to be done, it has to be done quickly and without a lot of debate.

Step Two: Deflect all specific attacks by not having a single bill with transparent provisions. On the House side, we’ve had a bill coming together that’s fairly detailed, and as recently as this morning, Speaker Pelosi was simultaneously insisting that she (1) has the votes to pass it and (2) was going to cancel the August recess to hold Members in town long enough to get the votes to pass it. At a minimum, there seem to be a fair number of nominally conservative “Blue Dog” Democrats who might vote for the House bill if forced to but would really prefer to have a bipartisan compromise emerge from the Senate instead. The Senate side has been much murkier, with support as well for a liberal bill like the House version but also a number of Democrats who are balking at the House’s rigid demands and a number of Republicans who won’t sign on to the House version but have left the door open to something different. In any event, it’s impossible to debate exactly what an “Obamacare” bill is at present, because there’s no one bill the White House is willing to publicly stand behind. Much of the Administration’s communications strategy has been based on deflecting criticisms by denying that this or that controversial provision has been set in stone, using (1) the shifting nature of the various bills and (2) those bills’ ultimate vagueness in passing on key decisions to an amorphous, yet-to-be-established bureaucracy as cover to stay unclear on how the pieces of the puzzle will fit together.

Let’s consider, just as an example, one of the most radical changes in national policy that may end up in the final bill – public funding of abortions. For three decades, the Hyde Amendment has codified the policy under which the federal government does not provide taxpayer money to subsidize abortions. This is the ultimate middle-of-the-road compromise (for pro-lifers, just refusing to subsidize isn’t nearly enough), but it maintains the pretense that the federal government is pro-choice rather than actively pro-abortion (if you subsidize something, you’re actively encouraging more of it). Repealing the Hyde Amendment as a stand-alone piece of legislation would require a major pitched battle and be an enormous flashpoint for putative moderate Democrats from districts with a lot of pro-lifers; instead, it may get done as part of a huge, sweeping overhaul that brings in scores of other dramatic changes (tax hikes, huge funding increases, changes in the way insurance, medical care and malpractice are handled) all at once.

So, how does President Obama respond to criticism that repeal of the Hyde Amendment is a step too far? Here’s what he told Katie Couric:

Katie Couric: Do you favor a government option that would cover abortions?

President Obama: What I think is important, at this stage, is not trying to micromanage what benefits are covered. Because I think we’re still trying to get a framework. And my main focus is making sure that people have the options of high quality care at the lowest possible price.

As you know, I’m pro choice. But I think we also have a tradition of, in this town, historically, of not financing abortions as part of government funded health care. Rather than wade into that issue at this point, I think that it’s appropriate for us to figure out how to just deliver on the cost savings, and not get distracted by the abortion debate at this station.

If Obama is serious about getting a public mandate for his bill, this isn’t at all an honest approach; either the final bill will continue to bar the use of public funds for abortions, or it won’t. But so long as he’s not defending any particular piece of legislation, he can keep doing this two-step.

The list of controversial issues goes on, almost endlessly. Much of the controversy focuses on the effects of various plans on existing private health benefits. And Obama can claim a strong mandate….against tampering with anybody’s existing health care. When John McCain proposed eliminating the favored tax treatment of employer-provided plans, Obama flooded the airwaves with ads hammering McCain for putting any sort of tax on anyone’s current health care. Obama may argue now that the various proposals are different – the main liberal plans don’t tax health benefits, they just use a variety of squeezes to try to drive them out of existence, but Obama’s (laughable) pledge to make his hugely expensive proposals “deficit-neutral” leaves the door open to the possibility that a final deal may incorporate any number of as-yet unspecified tax hikes (also in violation of other of his campaign promises). But then, McCain’s proposal also offset the taxes on employers with individual tax credits, and Obama pounced on him anyway, and ended up drawing substantial public support from people who – whether they knew that or not, having heard his barrage of ads – concluded that McCain would tax their health benefits and Obama would leave them in place. If proposals that tax or otherwise pressure existing benefits out of existence end up in the final bill, it will be quite a surprise to a lot of people who took Obama’s campaign ads and rhetoric seriously.

Step Three: Keep as many things on the hopper as possible. For much of the year, Obama has sought to simply overwhelm the Republican opposition by pursuing so many different things at once – the above-mentioned legislative agenda, the continuing parade of bailouts, the Sotomayor nomination, the overhaul of intelligence and detention policy – that undermanned, underfinanced and disorganized Republicans simply couldn’t get a hearing on all of them at once, and things could get done in Congress and the Executive Branch without a lot of scrutiny of the details. The apex of this strategy was the cap-and-trade vote that was buried in the news by the death of Michael Jackson.

This part of the strategy has broken down somewhat at the moment, as the President himself has now taken to talking almost entirely about healthcare. And that, in turn, has raised the political stakes, with Republicans openly declaring that health care is Obama’s Waterloo. From here out, it will be increasingly difficult for Obama to ram through a vote under cover of other events.

Step Four: Rush to get the bill into concrete form and passed with as little time as possible elapsed from Step Two. We saw this dramatically with the stimulus bill, which got passed without anybody in DC having read the whole thing and with hardly anyone having a firm grip on exactly what was in the bill that might later prove embarrassing to have supported. And predictably, the stimulus package is much less popular now than it was when it passed.

The rush to passage is effective for muting opposition. Pelosi’s desire to hold the House over August to vote would not only allow a rush to a vote, but would insulate her Members from spending a month in their districts hearing from voters while there’s a proposal on the table they have some chance of understanding. But it also means the Members vote before they have sold the public on the bill and everything in it. Even if you think that’s an appropriate way to make law in a democracy, as a matter of pure politics, it can be toxic later on. Even if the whole thing passed by the end of August, Republicans would have a year and a half to hammer on particular provisions of the bill ahead of the 2010 elections, and Democrats who voted for it could be caught offguard if they never spent a day guaging how individual parts of the bill would play in their states or districts.

Obama’s not worried about that – he can run for re-election on his personal popularity and the historic nature of his historic presidency. But Congressional Democrats won’t have that luxury – if you’re a white male supposedly moderate Congressman running for re-election in a district in Indiana or North Carolina where a majority of the voters are still old enough to remember when and why they voted for Bush in 2004, you need to be able to defend the actual policies you voted for.

Which may be why Obama’s hurry-up offense is at risk of a serious slowdown, with Harry Reid announcing today that unlike Pelosi, he’s not going to cancel the August recess or have a vote before then. Congressmen and Senators are nothing if not self-interested, and with Obama having burned a lot of political capital to get them signed on to the stimulus, the bailouts, and the cap-and-trade bill, and with polls showing sinking support for health care reform, many of them may be ready to decide that a full and open debate on the particulars of a particular bill, and some serious time discussing those particulars with the voters, may be necessary to get their votes on a final package. And that’s an outcome that can’t warm the heart of the White House.