Asked to explain the "second term curse," Mark McKinnon, a former adviser to Mr. Bush, attributed it to "fatigue, staff turnover and [the fact that] presidents' have usually moved off their top agenda items onto second-tier issues."

Historian Douglas Brinkley, meanwhile, argued that "the notion of the second term curse is a bit overplayed."

"It stems from the fact that two recent presidents, Richard Nixon and George W. Bush, had disastrous second terms," he said. "But really, a lot of the great presidents would never have made it into greatness without a second term. Take Bill Clinton. If it wasn't for the second term, Clinton wouldn't have been able to have the budget surplus, which is his great achievement now." Brinkley ticked off other second-term achievements, including Reagan's diplomatic successes in the Cold War and Dwight Eisenhower's establishment of NASA.

"President Obama shouldn't listen to all that noise about a second-term curse, because there's nothing to it," he said.

Still, Brinkley acknowledged that second-term presidents "start becoming irrelevant to the political process in the last two years." He said this is a time that presidents should focus on "big things" that are outside "the paradigm of just going mano-a-mano with Congress all the time."

"You travel a lot," he said. "You go to China and try to improve U.S.-China trade relations or try to make bilateral pollution standards. You try to make progress in the Mideast peace dilemma, you go to countries that have never had a presidential visit, where it would be historic. Perhaps you go to the Arctic, which is melting right now, with a bunch of climate scientists and glaciologists and talk about what's happening."

John Hudak, a fellow at the Brookings Institution, said there is a simple explanation for why so many presidents have seen scandal in their second term: They've been in office longer.

"The longer that time goes on, the more likely it is someone is going to get into some kind of trouble," he said. "Plus, there's more time for investigating a scandal. The scandals that come out in the second term often happened in the first term."

"If a scandal does come up, and you can almost be certain one will, I think President Obama's best approach is to look at what Presidents Reagan and Clinton did in dealing with scandal," Hudak continued. "The key for president Obama is to distance himself from it and work the press so he comes out of it looking like a.) he's still doing a good job running the country and b.) that his hands are clean, whether that's true or not."

After four years in Washington, Mr. Obama appears to have shifted from the more conciliatory tone he took with the GOP opposition early in his presidency toward a more oppositional stance, one illustrated by his recent refusal to negotiate on raising the debt limit. During a news conference last week, Mr. Obama said that he liked House Speaker John Boehner personally and had a "great time" golfing with him. But, he continued, "that didn't get a [grand bargain] deal done in 2011."