US President Barack Obama, looking to re-ignite his stalling presidency, used his first State of the Union address yesterday to implore Democrats and Republicans to overcome a "deficit of trust" in government and fix America's broken health care system, soaring deficits and polarized politics.

In his address before a politician-packed congressional chamber and a TV audience of millions, Obama vowed to deliver on the change he promised in his 2008 presidential campaign.

His No. 1 demand was for lawmakers not to abandon his prized health care overhaul, which is in severe danger in Congress.

"We face big and difficult challenges," Obama said, according to excerpts of his State of the Union address released in advance by the White House. "What the American people hope - what they deserve - is for all of us, Democrats and Republicans, to work through our differences, to overcome the numbing weight of our politics."

Obama sought to change the conversation from how his presidency is troubled - over the messy health care debate, a limping economy and the missteps that led to Christmas Day's barely averted terrorist attack - to how he is seizing the reins on the economic worries foremost on Americans' minds.

Obama was calling on Democrats and Republicans to "overcome the numbing weight of our politics" and come together around solutions to America's problems.

"We face a deficit of trust, deep and corrosive doubts about how Washington works that have been growing for years," he said, according to excerpts of the address released in advance by the White House.

He looked to rescue the sweeping health care plan, his top domestic priority. The plan was on the verge of passage, then got derailed after opposition Republicans captured a crucial Senate seat last week. The United States lacks universal health care.

Obama talked about Americans losing their insurance and patients being denied care. "I will not walk away from these Americans," he said.

Obama was standing before a country dispirited by unemployment in double digits and federal deficits soaring to a record US$1.4 trillion. He also faces a Democratic Party increasingly concerned about the fallen standing of a president they hoped would lead them through November's congressional and gubernatorial elections.

The president planned to spend about two-thirds of the speech on the economy, emphasizing his ideas for creating jobs, taming budget deficits and changing Washington's ways. These concerns are at the roots of voter emotions that once drove supporters to Obama but now are turning on him as he governs.

To address economic fears, Obama was prodding Congress to enact a second, debt-financed stimulus bill and to provide new financial relief for the middle class. To acknowledge frustration at the government's habit of spending more than it has, he will seek a three-year freeze on some domestic spending (while proposing a 6.2 percent increase in the popular arena of education) and announce he's creating a bipartisan deficit-reduction task force.

Even before Obama spoke, many of the proposals the White House revealed in advance were being dismissed - on the right or the left - as poorly targeted or too modest to make a difference.

Throughout, Obama aims to show he understands Americans' struggles to pay bills while big banks get bailouts and bonuses. Trying to position himself as a fighter for regular people, he will urge Congress to blunt the impact of last week's Supreme Court decision handing corporations greater influence over elections.

"I don't think American elections should be bankrolled by America's most powerful interests, and worse, by foreign entities," he said.

The guest list for first lady Michelle Obama's box in the gallery provided another vehicle for his message. It was featuring stories of success and hardship, from entrepreneurial immigrants to families trying to make ends meet.

With State of the Union messages constitutionally required and traditionally delivered at the end of January, Obama lucked into one of the presidency's biggest platforms just a week after Republicans scored an upset takeover of a Senate seat in Massachusetts. That election prompted hand-wringing over Obama's leadership and put a cloud of doubt over his agenda.

Republicans sought to capitalize on the Democrats' tough straits with their choice for the traditional Republican response: Gov. Bob McDonnell of Virginia, who took his state from Democratic hands two months ago.

McDonnell, in excerpts of his speech released in advance, said Democratic policies are resulting in an unsustainable level of debt. He said Americans want affordable health care, but they don't want the government to run it.

"Top-down, one-size-fits-all decision-making should not replace the personal choices of free people in a free market," McDonnell said.

Obama directed his speechwriters to resist pressure to produce what these addresses usually are: a feel-good assessment of America's health and a list of new proposals and priorities. Instead, Obama ordered up a more plainspoken narrative, hoping to tell the story of his presidency in a way that rekindles the energy he harnessed for his historic election.

Having already admitted he has failed to explain his agenda and connect with voters, Obama planned to further acknowledge missteps in communication and process. But he also planned an unapologetic defense of pursuing the same agenda on which he won.

That includes the health care overhaul, aggressively tackling global warming, sweeping changes to address the millions of immigrants in the US illegally and radical financial and educational reforms.

In a remarkable shift from past addresses, and notable for a president whose candidacy caught fire over his opposition to the Iraq war, foreign policy was taking a relative back seat.

The section will come second behind the economy and be largely devoid of new policy, with Obama providing an update on the Afghanistan escalation he ordered, looking ahead to the end of the US combat mission in Iraq and a nuclear weapons summit in Washington, and promising an aggressive fight against terrorists.