There's a number in the new Associated Press-GFK national poll that should put a scare into Democrats on the ballot this November.

Donkey. Also, elephant.  KAREN BLEIER/AFP/Getty Images

The number is 14.  That's the percentage point difference between those who say they favor a Republican-controlled Congress (51 percent) and those who want  Democratic-controlled one, among people who say they are strongly interested in politics. (Among the broader electorate, the Republican lead is far less consequential on this so-called "generic ballot" question with 37 percent choosing a GOP-controlled Congress while 36 percent opt for a Democratic one.)  According to AP's Jennifer Agiesta "in January, this group was about evenly split, with 42 percent preferring Democrats and 45 percent the Republicans."

Guess who votes in midterms -- and particularly the second midterm of a president's tenure? Yup -- people who are "strongly interested" in politics.  And therein lies the Democrats' problem.

And, it's not just the AP-GFK poll that shows a disparity of intensity between Democrats and Republicans.  A GW Battleground poll showed that 64 percent of Republicans are "extremely likely" to vote while 57 percent of Democrats said the same. In a CBS News-New York Times poll 81 percent of  Republican registered voters said they would "definitely" vote in November versus 68 percent of Democrats.

President Obama and his fellow Democrats are well aware of the party's enthusiasm problem. It's why at every fundraiser President Obama speaks at, he makes sure to include a line about how Democrats aren't as good at Republicans about turning out in midterms and how they need to get better at it. It's why Senate Majority Leader Harry Reid takes to the Senate floor at least once a week to attack David and Charles Koch.  The party's leaders are trying desperately to find a way to get their side excited about the elections and fully briefed on what's at stake.

The problem? Political enthusiasm is hard to create from out of nowhere. And, typically, the side most passionate about politics is the one motivated by negative emotions. Republicans hate Obamacare and don't like President Obama much either. (The same was true in 2006 with Democrats and George W. Bush.) There's no corresponding figure for Democrats to rally their dislike around. And, the positive emotions that drove Obama into office in 2008 have dissipated considerably over these past five years even within the Democratic base.

It's a huge problem for Democrats. And one without any obvious near term -- meaning between now and November -- solution.