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.

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.

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.

In the end, Tuesday's vote represented a repudiation of virtually every notion Democrats embraced in recent weeks as they tried to disregard the growing evidence that they were headed for a historic defeat. Now, the vote is in, and the voters' message can no longer be discounted.

Voters replaced Democratic senators with Republicans in Arkansas, Colorado, Iowa, North Carolina, Montana, South Dakota, West Virginia, and likely in Alaska, and appear on track to do so in a runoff next month in Louisiana. At the same time, voters kept Republicans in GOP seats in heavily contested races in Georgia, Kansas, and Kentucky. That is at least ten, and as many as a dozen, tough races, without a single Republican seat changing hands. Tuesday's voting was a wave alright - a very anti-Democratic wave.