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.

In the end, no single group will mean defeat for the Democrat and victory for the Republican in 2016. But President Obama's troubling legacy - a weakened coalition and growing ranks of alienated white voters - could mean a serious post-presidential hangover for Democrats.

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.

'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.'

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.

So Republican candidates bash Obamacare and move up in the polls. Given that public opinion remains firmly against the health care law - as it has been for years - that's not a shock. Democratic beliefs to the contrary are probably wishful thinking.

If one cannot imagine Obama saying such a thing — well, he didn't.