Obama will propose cutting Social Security and other government benefits by lowering the cost-of-living adjustment, putting a key GOP demand into his formal budget for the first time. The proposal would form part of a $1.8-trillion deficit-reduction plan that would also increase taxes, trim Medicare and eliminate the current across-the-board "sequester" cuts that Obama has called damaging to the economy.  White House officials confirmed the plan to reporters Friday, and both sides immediately began shooting at it. Critics on the left complained that Obama was proving himself a poor negotiator by opening new negotiations with what had been his final offer last year in talks with House Speaker John A. Boehner (R-Ohio).  "If you start with your best offer on the table, the question is where are you going to go from there?" said Jared Bernstein, a senior fellow at the left-leaning Center for Budget and Policy Priorities and a former member of Obama's economic team.  The proposal leaves Democrats "politically twisting in the wind," said Rep. Raul M. Grijalva (D-Ariz.), co-chairman of the Congressional Progressive Caucus, who called the cost-of-living change a "nonstarter."  Republican leaders insisted that Obama's plan did not cut Social Security and Medicare enough. Nor, they said, would they accept the new taxes the president wants.  Boehner said he had turned down Obama's offer in December for good reason: It was "significantly skewed in favor of higher taxes and included only modest entitlement savings."  "That's why his last offer was rejected," Boehner said in a statement. "At some point we need to solve our spending problem."  Those criticisms illustrate the difficult — perhaps impossible — path that Obama's plan would face to become law. But they also spotlighted the position on the political stage that White House officials were happy to claim for Obama: the man in the middle seeking to build a bridge.  "The offer that the president made to Speaker Boehner and which is incorporated in the president's budget is not the president's ideal approach to our budget challenges, but it is a serious compromise proposition that demonstrates that he wants to get things done," Press Secretary Jay Carney said.  Whether that image is real or political posturing has been the subject of endless discussion in Washington since Obama began to reach out to some congressional Republicans earlier this year. That effort is scheduled to continue Wednesday, when Obama plans a second dinner date with Senate Republicans just hours after his budget is formally released.  President Obama plans to reduce the deficit by $1.8 trillion over 10 years. Here's a breakdown:  Graphics reporting by Christi Parsons  If Republicans refuse the overture, as appears likely, the White House has calculated that Obama's outreach will at least show he tried to compromise.  The budget, which Obama is submitting to Congress two months late, will include some new goals — including money to expand early childhood education, which he would pay for with a new tax on cigarettes and other tobacco products — but the old goal of reducing the long-term deficit attracted most of the attention Friday.  His plan would change cost-of-living adjustments by adopting a so-called chained consumer price index, or CPI, that typically rises more slowly than the measure currently used. The new measurement, which some economists believe is more accurate, would shave a few dollars a month off the checks of retirees, veterans and others — many of whom depend on government programs.  But the impact on the budget would be big — about $390 billion over 10 years. About $120 billion of that would come from more revenue as tax brackets adjust more slowly for inflation. Obama would also seek $600 billion in new tax revenue by valuing income tax deductions claimed by Americans with incomes of $250,000 or more at 28%, rather than at their current, higher tax rates. And his proposal would limit the amount millionaires and billionaires can shelter in tax-deferred retirement accounts.  Obama would use a chunk of the CPI savings to provide additional money to the oldest and poorest seniors, cushioning them against the impact of the change — an element that White House officials stressed to calm opposition from the left.  Liberals were unmollified. Groups including MoveOn.org sent fundraising appeals to fight the proposal. In an open letter, Democracy for America Chairman Jim Dean warned Obama that on this issue, progressives "don't have your back."
WASHINGTON  &mdash; The budget that President  Obama  is scheduled to release next week drew attacks Friday from both the left and right &mdash; a reaction that  White House  aides appeared to welcome as they sought to portray the plan as a middle-of-the-road attempt at compromise.