Five weeks before Election Day and two days before the first presidential debate, a set of new polls shows that President Obama has a slight two-point edge over Mitt Romney nationally.

While both campaigns have tried to lower expectations for their respective candidate's debate performance, it's clear that conservatives expect Romney to use the debate to alter the campaign trajectory. The polls, meanwhile, show that there are also high expectations for Mr. Obama to perform well in the first debate.

In a new Washington Post-ABC News poll, Mr. Obama leads Romney among likely voters nationally, 49 percent to 47 percent. The poll shows Mr. Obama with a more comfortable lead in swing states, where he leads among likely voters 52 percent to 41 percent.

The Post poll gives Mr. Obama the advantage on nearly every major issue in the campaign, including taxes, social issues, women's issues, terrorism and ability to handle an "unexpected major crisis." On the critical issue of who voters trust to do a better job handling the economy, Mr. Obama and Romney are split at 47 percent for both.

Another poll, conducted for Politico and George Washington University, also shows Mr. Obama leading Romney among likely voters nationally, 49 percent to 47 percent.

Both the Politico and the Post surveys show Romney with a four-point lead among independents -- an edge that Romney will aim to build on Wednesday during the first presidential debate in Denver.

The Washington Post poll shows that most voters, 56 percent, expect Mr. Obama to prevail Wednesday night. Those expectations may work in Romney's favor, who "doesn't have to hit a home run," former House Speaker Newt Gingrich said Sunday on CBS' "Face the Nation."

"But Romney has to be, at the end of the debate Wednesday night, a clear alternative who is considered as a potential President by a majority of the American people," Gingrich continued.

On ABC's "This Week," former Mississippi Gov. Haley Barbour similarly said Romney has to offer a clear choice for voters.

"He has to get them back focused on the reality of Obama's policies, the failures of those policies, and then offer them what he would do and why that would be better for their families, their communities, and our country," he said. "Pretty simple. It's not rocket science."

The Washington Post's Chris Cillizza writes that Romney will have to step out of his comfort zone and go on offense against the president.

"It's clear that Romney is behind Obama nationally and in key swing states -- not so far behind he can't come back, but behind nonetheless -- and therefore needs to be the instigator," he wrote. "That's not a role Romney has been comfortable with in past debates. His attempts to go after McCain during the 2008 Republican primary debates often flopped, and Romney seemed uncomfortable playing too much offense in the brief moment when Texas Gov. Rick Perry (R) looked liked the 2012 front-runner."