When they were trying to convince House Democrats to take a suicide vote, the Obama administration argued that the national health care law would become more popular once passed. As recently as last month, House Speaker Nancy Pelosi declared that passage of the law would be an advantage to her party in the election.

Yet the New York Times today surveys the national campaign landscape, and finds Democrats still playing defensive on the new law. With few exceptions, candidates are either trying not to mention the law or are touting their opposition to it. In the West Virginia Senate race, one-time ObamaCare supporter Gov. Joe Manchin has reversed his prior support for the law and now calls for partially repealing it.

From the start, the project of repealing ObamaCare was going to be an uphill struggle just because it’s very difficult to undo acts of Congress. Even if Republicans were to take over both chambers and pass a repeal bill, Obama would veto it. Even if Republicans add the presidency in 2012, they’d have to find a way to get 60 votes in the Senate to fully repeal the law. 

Though the public wasn’t exactly rallying to support the law when Democrats were confidently defending it, by running away from it, Democrats virtually ensure that it will remain unpopular because the public will continue to be exposed more to the criticisms of the legislation than arguments in favor of it. As always, the possibility of GOP lawmakers becoming weak-kneed is the biggest obstacle to getting anything accomplished. But as long as ObamaCare remains unpopular and opposition is politically advantageous, it makes it more likely that Republicans will have the backbone to see through the repeal process. 

On top of repeal, the continued unpopularity of the health care law could bolster legal challenges to the law’s constitutionality. This was a point that Geoergetown Law Professor Randy Barnett emphasized to me when I spoke to him for a magazine piece.

“As public opposition to the mandate builds, this gives judges the fortitude they normally lack to enforce the Constitution against the will of Congress, which they deem to be the popular will,” he said. “If it’s not the popular will, they’re a lot more willing to strike down laws that they otherwise would uphold.”