(AP) - Six months in office, President Barack Obamasought to rally support for sweeping health care legislationWednesday night as Congress struggled to find agreement on ahistoric overhaul. He vowed to reject any measure "primarilyfunded through taxing middle-class families."

At a prime-time news conference, Obama defended his decision toset a midsummer deadline for the House and Senate to act, even ifit isn't met. "I'm rushed because I get letters every day fromfamilies that are being clobbered by health care costs, and theyask me can you help," he said.

The stakes are huge not just for everyday Americans, but alsofor Obama, who is putting much of his credibility on the line togain congressional passage. His stepped-up public role comes as hefaces rising criticism from Republicans, sliding public approvalratings and divisions within his party. Obama acknowledged thatmany people are uneasy about growing federal budget deficits andthe fast-rising government debt.

He said that without a deadline for action, a recent proposal tocurtail the growth in Medicare costs would not have materialized"until who knows when." He said in the past few days, leaders inboth houses had agreed to incorporate it into legislation takingshape.

Obama stepped to the microphone looking grayer than the man whoran for president and took office in January.

He said that since he moved into the White House, "we have beenable to pull our economy back from the brink."

Yet, he said, "of course we still have a long way to go."Obama didn't say so, but unemployment is expected to remainstubbornly high for many months to come.

He moved quickly into his pitch for health care legislation, anissue that now towers above all others - and has led at least oneRepublican to say that it could prove to be the president'sWaterloo if the drive collapses.

"This isn't about me. I have great health insurance and so doesevery member of Congress," he said.

The president said that in addition to helping millions who lackcoverage, the health care legislation is central to the goal ofeventually rebuilding the economy stronger than it was before therecession that began more than a year ago.

He said Medicare and Medicaid, government health care programsfor the elderly and the poor, are the "biggest driving forcebehind our federal deficit."

Unless they are tamed, he said to a national TV audience, "wewill not be able to control our deficit. If we do not reform healthcare, your premiums and out-of-pocket costs will continue toskyrocket."

The president said he believed it was possible to fund more thantwo-thirds of the cost of health care legislation by eliminatingwaste and redirecting federal funds already being spent. The restmust come from higher taxes, he said.

The administration proposed last winter a plan to raise taxes onupper-income wage earners by limiting their ability to claimdeductions.

Congress looked unfavorably on the proposal, and Obama said hewas open to alternatives - with one notable exception.

"If I see a proposal primarily funded through taxingmiddle-class families, I'm going to be opposed to it," he said.

It was not immediately clear whether the president was signalinghe would accept at least some higher taxes on middle-class familiesas the price for winning passage.

As a candidate he vowed repeatedly that no one earning under$250,000 would face higher taxes if he won the White House.

The president stepped to the microphone as Congress labored overhis call for legislation to expand health care to millions who lackit, as well as control the costs of medical care generally.

In his opening statement, he stressed the second of those twogoals.

"In the past eight year, we saw the enactment of two tax cuts,primarily for the wealthiest Americans, and a Medicare prescriptionprogram, none of which were paid for."

He vowed anew that he wouldn't sign health care legislation thatwasn't paid for, although his administration has exempted from thatpledge an estimated $245 billion to raise Medicare fees fordoctors.

"This debate is not a game for these Americans, and they cannotafford to wait for reform any longer," Obama said. "They arelooking to us for leadership. And we must not let them down."

Holding his 10th extended news conference, Obama was renewing amessage that the White House says he cannot pound enough: makinghealth coverage affordable and sustainable is so vital thatanything less will erode the economic stability of families,businesses and even the government.

The complex work of getting bills through the House and Senateis proving difficult. Republican leaders contend Obama's effort andthe emerging bills are rushed and risky, and members of Obama's ownDemocratic Party are split on how to structure and pay for adaunting overhaul.

Obama sought to get beyond that and connect with Americans -and, in turn, the White House hopes, to pressure Congress. "Iunderstand how easy it is for this town to become consumed in thegame of politics, to turn every issue into a running tally of who'sup or who's down," he said.

His words came as House Speaker Nancy Pelosi said Democrats havethe votes to pass a massive health care bill in that chamber,prompting surprise and some criticism from conservatives within herparty.

Congress is struggling to figure out how to pay for addingmillions to the ranks of the insured and slowing the long-termcosts of health care in the U.S.

In his comments, Obama reiterated his pledge that any bill hesigns will not add to the nation's soaring deficit. "And I meanit," he said.

Meanwhile, a nervous public is being hit by TV ads and claimsfrom all sides.

And other issues haven't gone away as Obama steps before thecameras. Still looming are an economy that keeps losing jobs, warsin Iraq and Afghanistan and Obama's January deadline to shut downthe Guantanamo Bay detention facility.

He wants the House and Senate to vote on comprehensive healthcare bills before they break for the summer, a window that isscheduled to shut by the first week in August. That timetable isgrowing tenuous, though, with up-and-down developments by the day.

So Obama is everywhere on health care: giving Rose Gardenstatements, visiting health clinics, talking to bloggers, grantinginterviews.

Obama's approval rating stands at 55 percent, according to a newAssociated Press-GfK poll, down from 64 percent in late May andearly June. Some 50 percent approve of his handling of health care,but 43 percent disapprove, and that number has risen sharply sinceApril.

With public opinion still waiting to be shaped on health care,and with the legislative details in flux, what's clear is thatpeople care.

Nearly 80 percent of those polled say health care is animportant issue to them. Obama is seeking to extend coverage tomillions who don't have it and to hold down the long-term costs ofhealth care. How to pay remain a complex political question.

It didn't help the White House when the Congressional BudgetOffice last week said the bills moving through Congress would addto the nation's long-term costs, not reduce them. Obama has beenemphatic that he will not sign a bill that adds to the government'sdeficit.

Meanwhile, unemployment is at 9.5 percent and rising.

Talk of Obama inheriting an economic mess from George W. Bush isfading, and the American public is now grading the new president.His approval rating on handling the economy has been slipping asimpatience grows.