WASHINGTON - (AP) - Challenging Republican budget plans, PresidentBarack Obama on Wednesday proposed lowering the nation's futuredeficits by $4 trillion over a dozen years through a blend ofspecific measures and vague objectives designed to lower spendingin politically sensitive health care programs while also increasingtaxes.

The president proposed reductions in the growth of Medicarespending, cuts in defense, an overhaul of the tax system toeliminate many loopholes enjoyed by individuals and corporations,and an end to Bush-era tax cuts for wealthier Americans.

"We have to live within our means, we have to reduce ourdeficit, and we have to get back on a path that will allow us topay down our debt," Obama said in a speech at George WashingtonUniversity.

As much a policy speech as it was a political address, Obamalaid the blame for the rising debt on the spending increases andtax cuts enacted during the presidency of George W. Bush and therecession that struck in late 2007. "We lost our way," he said.

Ensuring that the nation's fiscal health will be at the centerof the 2012 presidential election, Obama drew sharp contrasts witha Republican plan that cuts about $5.8 trillion in spending overthe next decade and which the White House says unfairly singles outmiddle-class taxpayers, older adults and the poor.

Such cuts, he said, "paint a vision of our future that's deeplypessimistic."