As we point out in 
Epic Journey, Barack Obama ran as the anti-Bush, and used antipathy to the incumbent to stoke passion.  Now that he is the incumbent and Bush is in the nation's rearview mirror, things have changed.  
Public Policy Polling reports:
Perhaps the greatest measure of Obama's declining support is that just 50% of  voters now say they prefer having him as President to George W. Bush, with 44%  saying they'd rather have his predecessor. Given the horrendous approval ratings  Bush showed during his final term that's somewhat of a surprise and an  indication that voters are increasingly placing the blame on Obama for the  country's difficulties instead of giving him space because of the tough  situation he inherited. The closeness in the Obama/Bush numbers also has  implications for the 2010 elections. Using the Bush card may not be particularly  effective for Democrats anymore, which is good news generally for Republicans  and especially ones like Rob Portman who are running for office and have close  ties to the former President.
Passage of health care reform might not help the president or his party.  
Resurgent Republic reports:
Given the disproportionate share of voters age 55 and older likely to comprise  the electorate in next year’s mid-term, passage of health care reform  legislation would pose a serious risk to Democratic majorities in the House and  Senate according to a new survey released today by Resurgent Republic, a  non-profit conservative organization that gauges public opinion toward  government policy proposals.
The nationwide survey of 1000 voters age 55  and older had a sample in which Democrats enjoyed a seven percentage-point  advantage over Republicans (32%-25%) and President Obama enjoyed a favorable  rating of 53%.  These numbers are similar to recent surveys of voters of all  ages.  However, voters 55 and older opposed health care reform being debated by  Congress by 48-39%, with intensity running strongly against the legislation’s  proponents (40% strongly opposed versus 25% strongly support).  This opposition  correlated with pluralities now holding a favorable view of Republicans in  Congress (46% favorable-42% unfavorable) and an unfavorable view of Democrats in  Congress (44% favorable-45% unfavorable), despite the partisan identification of  the sample favoring Democrats.