The Obama damage is two-fold. First, his success relied on a coalition that likely will not survive, or at least survive at full strength, without Obama himself on the ticket. Secondly, Obama drove a significant portion of white voters away from the Democratic Party.

As Democratic losses mounted in Senate races across the country on election night, some liberal commentators clung to the idea that dissatisfied voters were sending a generally anti-incumbent message, and not specifically repudiating Democratic officeholders. But the facts of the election just don't support that story.

Polls suggest that more and more, opposition to Obamacare is based on voters' personal experience, and not just on what they have heard or read about the law.

Perhaps the most striking thing about the 2015 State of the Union address was not the president at the podium but the audience in the seats. The joint session of Congress listening to President Obama Tuesday night included 83 fewer Democrats than the group that heard Obama's first address in 2009 - 69 fewer Democrats in the House and 14 fewer in the Senate. The scene in the House Chamber was a graphic reminder of the terrible toll the Obama years have taken on Capitol Hill Democrats.

That does almost nothing to address voters' concerns, which remain a potent factor in the campaign. The bottom line is, there's a reason Republicans keep pushing so hard against Obamacare: So far, it's working.

'I haven't used the veto pen very often since I've been in office,' Obama told NPR. 'Now, I suspect there are going to be some times where I've got to pull that pen out. And I'm going to defend gains that we've made in healthcare; I'm going to defend gains that we've made on the environment and clean air and clean water.'

Now that the 2014 elections are over and national politics is all about 2016, Democrats have good reason to worry that, for all his success at the polls, President Obama will leave his party with a toxic legacy.