Mr. Obama's speech sharpened his message to voters about the difference between what he calls his balanced and fair budget proposals, and those of opposition Republicans, including that party's presidential hopefuls.

　　Last week, the Republican-controlled House of Representatives approved a 2013 federal budget proposal, a $3.5-trillion plan that Republican frontrunner Mitt Romney has endorsed.

　　It would cut deficits over the next decade by trillions of dollars more than President Obama has proposed, by eliminating tax loopholes and targeting programs that primarily help low income Americans.  It also includes tax cuts that favor wealthier Americans.

　　Addressing Associated Press editors and publishers here in Washington, Mr. Obama, a Democrat, called the Republican proposals a "recipe for decline" that would have devastating consequences for the middle class. "It is a Trojan horse.  Disguised as deficit reduction plans, it is really an attempt to impose a radical vision on our country.  It is thinly veiled social Darwinism.  It is antithetical to our entire history as a land of opportunity and upward mobility for everybody who is willing to work for it," he said.

　　Mr. Obama said the Republican budget would "gut" investments in education, training and research necessary to build a strong U.S. economy.

　　The president said broad-based prosperity has never "trickled down from the success of a wealthy few," but has come "from the success of a strong and growing middle class."  He accused Republicans of promoting a radical plan. "This isn't a budget supported by some small rump group in the Republican Party.  This is now the party's governing platform.  This is what they are running on," he said.

　　Mr. Obama repeated his call for Congress to make the tax code fairer by requiring wealthy Americans to pay higher federal income taxes.

　　He said the Republican budget would "end Medicare as we know it" and again said he is confident that the Supreme Court will exercise "restraint" and uphold the constitutionality of his signature health care law.

　　Republican reaction was swift.  A Romney campaign spokesperson called Mr. Obama unqualified to lecture on responsible federal spending because he had "piled on" trillions of dollars in new debt while in office.

　　The Republican Speaker of the House of Representatives, John Boehner, accused Mr. Obama of "resorting to distortions and partisan potshots" and recommitting to policies that have worsened the U.S. debt crisis.

　　President Obama's speech came as Romney hoped to further solidify his frontrunner status for the Republican presidential nomination in primary contests in Wisconsin, Maryland and Washington.