President Obama's State of the Union address Tuesday comes at a critical moment in his presidency, with many Americans doubting his ability to mend the economy as he prepares to start his re-election bid. Obama also faces a delicate epoch in American politics, with voters sick of corrosive partisan bickering and lawmakers choosing their fights and words carefully after the recent mass carnage in Tucson.

But just below the surface is a brewing confrontation with congressional Republicans determined to undermine Obama's efforts to reposition himself as a centrist and reclaim the support of independents he's lost since 2008.

"Watch for the president to lay the foundation of the re-election campaign by appealing to mainstream America," said Mark Daley, a Democratic strategist and former campaign spokesman for Hillary Clinton. "The Republican numbers look nothing like they did in November and the president will seize the opportunity to win over folks who are bothered by the partisanship and gridlock that has overtaken the Beltway."

Two new polls out late last week underscored some of Obama's challenges. A Fox News poll found 90 percent overall view the economy in a negative light, and 51 percent rate it as poor. The same poll found that 32 percent believe Obama's policies have hurt the economy compared with 28 percent who believe they helped and 37 percent who say Obama made no difference.

An Associated Press-GfK poll found 57 percent believe the country is headed in the wrong direction compared with 37 percent who believe it's heading in the right direction. Fifty-three percent said they disapprove of Obama's handling of the economy compared with 47 percent who approve. At the same time, 53 percent said they approve of the job Obama is doing overall -- a slight boost in his popularity that gives the president something to build on.

Robert Lehrman, former speechwriter for Vice President Al Gore, said State of the Union addresses tend to follow the same script.

"The state of the union is strong, and have we done a lot of good things? And the answer is yes," Lehrman said. "Then he will have a list of things to do all couched to sound reasonable, and are we going to succeed? Yes, but the way forward won't be easy."

Everything hinges on the economy coming back, Lehrman said. But Obama will also spend some time talking about the mass shooting in Tucson that killed six and left 13 injured, including Rep. Gabrielle Giffords, and the need for civility in politics while striking conciliatory tones with Republicans.

The White House so far isn't saying what is in the president's speech, but he is expected to take an active role in writing and revising it.

Clark Ervin, a scholar at the Aspen Institute who served on Obama's transition team, said the time is right for Obama to focus on fiscal concerns and especially the deficit.

"My sense is he has built some momentum, but the question is what are Republicans going to do about it?" Ervin said. "The risk for the them is that their new Tea Party base is going to force them so far to the right that the president is going to have the center all to himself."