WASHINGTON, Feb 23 (Reuters) - Large majorities of Americans support U.S. President Barack Obama's plans to revive the economy and his efforts to work across party lines, according to a pair of public opinion polls released on Monday.

One month into his presidency, a Washington Post-ABC News poll found 68 percent of Americans approve of Obama's job performance.

Sixty-four percent of respondents supported the administration's $787 billion economic stimulus package and the same percentage backed his proposal to prevent housing foreclosures, the Washington Post reported.

According to a New York Times/CBS News poll, Obama has a 63 percent job approval rating and more than 75 percent of Americans are optimistic about the next four years with him as president.

The poll results provide Obama with substantial political results as he confronts the U.S. economic challenges and opposition from nearly all Republicans in Congress, The New York Times said.

Obama, a Democrat, succeeded former Republican President George W. Bush last month. His current term in office goes through January 2013.

The polls were released on the eve of Obama's first address to a joint session of Congress, where he is expected to talk about the emergency economic spending law.

Both polls found widespread support for Obama's effort to bridge the partisan divide in Washington and found fault with Republicans for balking.

In the New York Times/CBS poll, about 75 percent of respondents, including 61 percent of Republicans said Obama has been trying to work with Republicans.