* Obama administration hopes plan is "path to a deal"
* Cuts to Social Security retirement program loom
* Proposal would trim $1.8 trillion from deficit in 10 years
The White House proposed a budget on Wednesday that would trim the U.S. deficit over three years by requiring millionaires to pay more in taxes and enacting spending cuts to replace the "sequester" reductions that went into place last month.
President Barack Obama's $3.77 trillion budget blueprint for fiscal 2014, which begins Oct. 1, combines cuts in Social Security retirement benefits - opposed by many Democrats - with tax increases for the wealthy - opposed by many Republicans - to achieve deficit reduction that both parties want to accomplish.
The Democratic president's budget stands little chance of being enacted into law and is meant to serve largely as a negotiating tool for an elusive deficit-cutting deal with Republicans in Congress.
Senior administration officials said that, in spite of Republican leaders' resistance to tax increases, they hoped Obama's plan could lead to an accord.
"This is an offer where the president came more than halfway towards the Republicans in an attempt to get a fiscal deal," an administration official told reporters.
"There continue to be people who are on the Republican side ... in the Senate at least, who are saying things that would give you some hope that there is a path to a deal."
The budget revives long-standing principles that Obama has said are critical to deficit reduction and economic growth. It ensures that those making $1 million a year or more would have to pay at least 30 percent of their income in taxes, after gifts to charity, officials said.
That increase, along with spending cuts and a 28 percent cap on tax deductions for high earners, would bring the U.S. budget deficit down to 2.8 percent of GDP by 2016 and 1.7 percent by 2023, they said. The nonpartisan Congressional Budget Office in February projected the U.S. deficit to be 5.3 percent of GDP this year.
Obama is due to release his full budget at 11:15 a.m. EDT (1515 GMT) and to make remarks at that time.
The president's advisers said the budget proposal would achieve $1.8 trillion in deficit reduction over 10 years. Added to the $2.5 trillion in deficit cuts from past efforts, the total would be above the $4 trillion reduction both Republicans and the White House have said would be an acceptable goal.
Republicans quickly dismissed Obama's proposal, particularly his deficit-reduction plans.
"When you cut through the spin and get to the facts, it looks like there's less than $600 billion worth of (deficit) reduction in there - and that's over a decade - all of it coming from tax increases," said Don Stewart, a spokesman for Senate Republican leader Mitch McConnell.
"In other words, it's not a serious plan. For the most part, just another left-wing wish list," he said.
The U.S. Chamber of Commerce, a business lobbying group, lambasted the White House for advocating tax hikes.
LOOKING FOR A DEAL
Obama is trying to use his budget to relaunch talks over a long-running fiscal battle with his adversaries in Congress.
To do so, Obama is offering a concession that has enraged many of his supporters: adopting a less generous measure of inflation to calculate cost-of-living increases for the beneficiaries of many federal programs. One result would be diminished benefits for most recipients of the Social Security retirement program.
Although Obama has pledged to shield some of the most vulnerable beneficiaries, the proposal has drawn strong opposition from some fellow Democrats and groups representing labor.
Republicans largely reject proposals for additional tax revenues.
Obama's hope is to build a coalition of lawmakers willing to compromise, although most observers see that as unlikely. He has invited 12 Republicans to dinner at the White House on Wednesday.
Both sides are so dug in that they were unable to prevent some $85 billion in across-the-board "sequestration" spending cuts from going into effect March 1.
Obama's budget proposal would replace those cuts with his original deficit-reduction proposal from December. That offer included $930 billion in spending reductions and some $580 billion in tax revenues.
The budget forecasts a $744 billion deficit in 2014, which is 4.4 percent of GDP.
In line with proposals from his State of the Union address, Obama's budget includes spending on policy priorities such as infrastructure and early childhood education. He would pay for those programs with additional taxes and the elimination of some tax breaks for the wealthy.
The budget also includes a 10 percent tax credit for small businesses that raise wages or hire new workers.
Obama's budget is a clear contrast with a rival blueprint by Representative Paul Ryan, the 2012 Republican vice presidential nominee and potential 2016 presidential candidate.
Ryan's plan aims to balance the budget in 10 years through deep cuts to healthcare and social programs while lowering tax rates.
"The real question I want to know is: When does he balance the budget? Does he propose to ever balance the budget?" Ryan said on MSNBC's "Morning Joe" program.