On a conference call this morning, the Clinton campaign called on Barack Obama to take down an ad that aired in New Hampshire last night in which they say Obama falsely claims his plan "covers everyone." Heres' the ad:

Clinton Campaign Manager Patti Solis Doyle has written a letter (pdf)to her counterpart at the Obama campaign, David Plouffe, which reads, in part:

Your advertisement not only contradicts the judgment of health care experts, but public statements by your campaign and your candidate. Senator Obama has pledged to put "honesty first" in this campaign. In that spirit I respectfully request that you stop running this ad which is misleading voters in New Hampshire.

In the Q&A portion of the call, Clinton spokesman Howard Wolfson was asked to explain why Hillary has gone negative recently and whether it's because, as her rivals assert, she's sliding in the polls. Wolfson responded that both Obama and Edwards had been attacking Clinton on a near daily basis for months, adding:

"That's not the way we'd hope this campaign would go. It was not our choice to engage in that. That was a strategy that they chose to employ. Senator Obama, deliberately eschewing the politics of hope - deciding that the politics of hope were not working for him, and Senator Edwards, of course, abandoning his pledge in 2003 and 2004 to run a positive campaign.

It was important for us to correct the record and make sure that people knew the facts. You can never be in a situation where you're opponents are attacking you relentlessly and distorting your record and not respond. So that is what we are doing in this instance."

Wolfson was also asked why they were attacking Obama over this ad now, since it appears the ad was created (and may have even aired) some two months ago. Wolfson said this was the ad was brought to their attention by some of their people who saw it air yesterday in New Hampshire, before seguing to the real reason:

"Look, we've had a great debate about healthcare this week. We're talking about an important, substantive issue that voters care about. And on that important, substantive issue there are important, substantive differences. And Senator Obama is not getting the bettter of that debate because he has a plan that leaves 15 million people out. Therefore he chose, I guess, to put this ad up to make up for his weakness, to make up for the fact that he leaves 15 million out, and we want to make sure that voters get the truth. And if Senator Obama perceives weakness in this debate, we're not going to allow him to compensate for that weakness by misleading voters as to whether or not his plan covers everyone, because it doesn't."

And, incidentally, to the point Steven Stark made earlier, there was more than one mention of Paul Krugman's column this morning.