The Illinois senator's lead over presumptive GOP nominee John McCain has tightened in some recent polls, while expanding in others.
Rep. John Dingell of Michigan -- a battleground state -- is among those concerned over the trend, The Hill reported Monday. He warned Obama that the GOP will "run a very rough campaign against him," the newspaper reported.
A CNN poll released Monday indicated Obama and McCain are running neck-and-neck, while the most recent Gallup-USA Today poll of likely voters showed Obama leading McCain by 48-45.
"The campaign has not yet taken off," Dingell said. "He's got to address things that go into a presidential campaign as opposed to a primary campaign. They're very different campaigns."
Sen. Dick Durbin of Illinois, the co-chairman of Obama's campaign, said Obama's drop in the polls is at least partly attributable to a reduced presence in the news cycle while he was vacationing in Hawaii this month, while Russia's invasion of Georgia gave McCain a chance to dominate the headlines.
"We realize over the last week or 10 days that John McCain has had a 12-0 run in this basketball game," Durbin said. "We know the momentum can shift."