Democrats seized Wednesday evening on a controversial billboard in Iowa comparing President Obama to Nazi leader Adolf Hitler and Soviet leader Vladimir Lenin.

Democratic National Committee (DNC) Executive Director Jen O'Malley Dillon pounced on the billboard sponsored by a Tea Party group in a fundraising pitch, linking it to Republican officeholders and candidates.

"Tthink comparing a president of the United States to totalitarian dictators responsible for mass murder is appalling," the DNC's executive director wrote in a fundraising email sent to be sent tomorrow. "I think calling Barack Obama a socialist is nonsensical. But I don't think any of this is surprising."

"Republicans keep saying that they aren't extremists -- but they keep doing things like this," she added. "And don't let the tea party label fool you -- these people are Republicans, and the only thing that scares me about them is that they're fired up to vote in November."

The billboard depicts Obama between images of Lenin and Stalin, with the admonition, "Radical leaders prey on the fearful & naive."

The ad, paid for by the North Iowa Tea Party, drew immediate criticism, prompting the group to take down the ad on Wednesday.

The DNC email asks for donations, in particular noting Republicans' similarly harsh rhetoric at times toward the president.