The president’s poll numbers took a hit during the health care rollout and have never fully recovered. The law also caused Democrats in general to lose their advantage in voters’ preference for control of Congress, according to a CNN/ORC poll conducted in December. Furthermore, most Americans disapprove of the health care law.

The Republican plan is simply to hold tight to last year’s disapproval and drag it forward to this year’s election. And that just might work. Democrats have so fumbled the selling of the health care law’s advantages, both moral and economic — faltering and stammering when they should have been steadfast and resolute — that they have acquiesced the debate to Republican opposition.

Rather than fight back with facts, too many Democratic politicians tucked their tails and ran away from the law, or, worse yet, joined the attack.

In addition to the effectiveness of Republican attacks and the anemia of Democratic support for the law, the demographics of midterm voters also bode well for Republicans.

Midterm elections generally skew older and whiter, and Republicans are counting on this skew to give them an electoral advantage. According to a Washington Post/ABC poll released at the end of last month, whites and elderly people are the least likely to support federal changes to the health care system, yet most elderly people are beneficiaries of another, quite successful government health care program: Medicare. And 77 percent of Medicare beneficiaries are white.

Even if Obamacare were not a factor, history suggests that this midterm election would still be a tough one for Democrats. As The Washington Post’s Chris Cillizza pointed out in February:

“The party of a re-elected president tends to get walloped in the following midterm election. Since 1912 (that’s when the House expanded to 435 seats), the president’s party has lost an average of 29 House seats in the following midterm election.”

The health care law is working, insuring millions of Americans at far less a cost than what was previously estimated. But this civic victory may well contribute to a political defeat in November, unless Democrats can upend historical precedent and change the profile of the people who vote in off-year elections.

Our elections have been severely altered by a corporatist Supreme Court, maleficent voter ID laws and gerrymandering run amok. In the face of it all, can Democrats gather the gumption to say, “Enough”?