As President Obama gets set to sign the Democrats' healthcare reform bill, a new CNN poll shows that for the first time a majority of Americans disapprove of his job performance.

According to a CNN/Opinion Research Corporation poll released Monday, 51 percent of respondents disapprove of the president's job performance while 46 percent approve. The survey of some 1,000 registered voters was conducted before the healthcare bill passed the House on Sunday.

Still, Obama remains personally popular – 70 percent of respondents said they approve of him "as a person." And it's that statistic that vulnerable Democrats are likely considering as the campaign season starts.

White House Press Secretary Robert Gibbs said last week that the president will soon be out on the trail. "I expect this President will spend a lot of time on the campaign trail when it's time to spend time on the campaign trail," Gibbs told reporters.