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WASHINGTON -- Reaching for a game-changer, President Barack Obama is beset by conflicting goals in a prime-time address Wednesday expected to detail just how he wants to expand health care coverage and lower medical costs while signaling to a deeply divided Congress that he's ready to deal.

And show the public he's in control.

The president is likely to say that a government-run insurance plan, known as the "public option," will not provide a level of subsidies that give it an unfair advantage over private insurers, aides familiar with the speech preparations told The Wall Street Journal.

Insurers oppose the public option, saying it will lead to excessive government control of health care and could eventually drive them out of business. Republicans say they won't support an overhaul with a public option, and liberal Democrats say they won't support one without it.

Even as Obama prepared to speak to lawmakers and a live television audience, the leader of the influential Senate Finance Committee raced to broker a bipartisan agreement on the president's top domestic priority.

The White House set a high bar for the rare presidential address to a joint session of Congress, acknowledging the huge stakes and creating big expectations about the level of specificity Obama would provide. The president has stressed repeatedly the broad goals for the sweeping health care overhaul he seeks, but has left the details to lawmakers. Through a hot summer of angry debate, he lost his grip on the process.

Aiming to reclaim it at a pivotal moment and open a final push for a bill, Obama said, "We do intend to get something done this year."

"I'm open to new ideas," he said in an interview for broadcast Wednesday on ABC's "Good Morning America" in which he previewed the themes of his speech. "We're not being rigid and ideological about this thing."

With the approximately 35-minute speech still being written, much by Obama himself, White House officials said the president will "answer all the major questions" -- including the sticky issue of how to pay for getting coverage for the 50 million Americans who lack it.

"Everyone who listens will understand that his plan has at its core two overriding goals -- to bring stability and security to Americans who have insurance today, and affordable coverage to those who don't," Obama senior adviser David Axelrod said.

It was unlikely that Obama would issue explicit veto threats, as he prefers to focus on what he is for rather than on what he will refuse to support, aides said. He also wasn't delivering a piece of legislation to Capitol Hill, where three House committees and one in the Senate already have devised their own, partisan versions.

Obama will appear before lawmakers a day after their return from an August recess marked by contentious town halls and much misinformation and confusion about what a health care overhaul may look like.

A senior administration official said Obama has ceased worrying about whether he gets any Republican participation. "If they don't want to, we can't worry about that," said the official, who spoke on condition of anonymity to more freely discuss behind-the-scenes thinking.

But that is no longer Obama's biggest difficulty, a fact underscored by the conflicting advice he was getting from within his own party.

Rep. Zack Space, D-Ohio, a member of the fiscally conservative Blue Dog coalition, said Obama should "appeal to both sides of the aisle, and to everyone involved in this situation, to embrace a sense of compromise and moderation."

But Rep. Raul Grijalva, D-Ariz., co-chairman of the House Progressive Caucus, said he wanted Obama to state his unequivocal support for a government-run health insurance option to compete with private companies, and to clearly distance himself from the two alternatives now circulating.

One of those would structure a public plan so that it would be triggered only if private insurance companies weren't providing enough affordable choices in certain areas; the other would set up nonprofit co-ops.

Sen. Max Baucus, D-Mont., chairman of the Senate Finance Committee, circulated a proposal that would cost $900 billion over 10 years and guarantee coverage for nearly all Americans, regardless of medical problems. Fees on insurers, drug companies and others in the health care industry would finance tax credits to help expand coverage. Baucus' panel is the only one of the five involved in health care not to complete a bill yet, and the only one still searching for a bipartisan compromise.

One provision would fine families up to $3,800 for failing to buy health insurance, essentially requiring that everyone have medical coverage, much like the case with car insurance. Obama rejected a mandate, and fines, during his presidential campaign.

Baucus asked his "Gang of Six" bipartisan negotiators to report back with suggestions by Wednesday morning. "I made that clear, that the bipartisan effort will have more effect if there's agreement prior to the president's address," he said.

But few appeared ready to do as Baucus wants and move before hearing from the president. "That's the cart before the horse, as they say in Maine," said Sen. Olympia Snowe, a moderate Republican being courted by the White House.

Like bipartisanship, prospects for a government-run insurance plan also dimmed. It is not in Baucus' plan, and two prominent House Democrats backed away from it Tuesday.

It is this issue that has become Obama's main quandary.

Gibbs said Obama would explain why he supports a public option -- and how it wouldn't be "some grandiosely subsidized, unlevel playing field" that would drive private insurers out of business. But there's no sign Obama will draw a line in the sand over it.

House Speaker Nancy Pelosi said Obama told her and Senate Majority Leader Harry Reid during a White House meeting Tuesday that his message would essentially be: "If you have a better idea, put it on the table."

The Associated Press contributed to this report.