In terms of telling the American people and Congress exactly what he wants in the huge health care reform he's seeking, President Obama seems determined to leave the fine print to Capitol Hill. That was one signal from his primetime news conference designed to rally public support for his principal domestic undertaking in social engineering.

The president was clear on what he doesn't want — any taxes that would fall on the middle class, which not surprisingly continues to be his own special interest. In the Democratic Party that once declared itself the party of the little guy — the poor and the disadvantaged — Main Street has become more the focal target than the side streets where the bottom-feeders dwell.

In one transparent gesture to the broad middle class, Obama in his latest meeting with the press indicated he would agree to raise the floor on Americans exempt from higher income taxes to pay for health-care reform.

He would lift it from annual earners of $350,000 to $1 million, as some House negotiators have proposed.

"If I see a proposal that is primarily funded through taxing middle-class families," the president said, "I'm going to be opposed to that." At the same time, he allowed, the plan to hit the higher earners with a surcharge "meets my principle."

Obama told reporters that two-thirds of the cost of his ambitious health care revamping would be borne through a range of savings in the existing system, with the remaining one-third paid by the highest-income Americans.

To most wage earners on Main Street, sticking fellow citizens who are pulling in a million bucks or more a year is not likely to be considered a hardship.

But the concept is an open invitation to Republican political strategists, desperate to find a winning strategy against Obama, to trot out their old "class warfare" lament against the party of FDR and LBJ.

Conservatives have already been beating their ideological drums against what they see as an Obama conspiracy to "redistribute the wealth" through a range of tax policies and programs beneficial not only to the poor but the imprecisely defined middle class as well.

In the shorthand of conservative politics, that spells the dreaded "socialism," though the concept has long been imbedded in such desired programs as Social Security, Medicare and Medicaid. The public acceptance of all three is beyond question today. Witness, for example, the fate of the feeble and foolish efforts of the departed Bush administration to, as the Democrats put it, "privatize" Social Security through investment of welfare payroll taxes in the stock market.

But conservative Blue Dog Democrats, some of whom embrace the concern over redistributive tax policies, are pushing back against the trillion-dollar-plus Obama schemes for health care reform as well as for economic stimulus and recovery.

The Blue Dogs' existence, and tenacity, can undercut the numerical majority advantage Obama enjoys in Congress, justifying his continuing quest for a few moderate Republican votes in both the House and Senate to get what he wants.

This reality dictates his reluctance to thumb his nose at the Republicans on Capitol Hill and simply rely on his own party to get health care reform across the finish line. He may still have to resort to that, but it looks very much as though he lacks the votes, in any event, to get health care legislation by his declared deadline, before the August congressional recess.

It seems likely Obama is going to have to plunge more personally and explicitly into the debate by engaging himself in the sausage making on the Hill, rather than hopefully awaiting a satisfactory health care package pounded out in the various committees working on it.

The buildup that Obama has given to the imperative for sweeping reform in this field has made the outcome critical to establishing and maintaining momentum for his even broader domestic agenda.

With his personal public support still impressive but his policies suffering erosion in the polls, Obama needs success on this one to sustain a semblance of the euphoria that greeted his election only eight months ago.