Apparently, Sheryl Crow can't touch Deputy White House Chief of Staff Karl Rove on the topic of global warming.

The singer and Laurie David, her partner on the Stop Global Warming College Tour, had a less than friendly encounter with Rove at the White House Correspondents' Dinner Saturday, according to numerous published reports.

The trouble reportedly began when Crow and David approached Rove at the event and urged him to take a "fresh look" at the science of global warming.

According to David's account of the exchange, which was published on the Huffington Post, the senior White House advisor "immediately got combative," and launched into a defensive recitation of the administration's global warming policy.

When Crow laid a hand on Rove's arm to try and diffuse the situation, he shook her off, snapping, "Don't touch me!"

Crow responded, "You can't speak to us like that, you work for us," to which Rove replied, "I don't work for you; I work for the American people."

"We are the American people," Crow reminded him.

David, the producer of an Inconvenient Truth, described Rove as "dismissive, condescending, and quite frankly a bully."

"Drama aside, you would expect as an American citizen to be able to engage in a civil discussion with a public official," she wrote.

Relating his version of the incident, Rove told the Washington Post that David "came over to insult me, and she succeeded."

Meanwhile, White House spokesman Tony Fratto accused Crow and David of "going after officials with misinformed assertions at a social dinner."

"It would be better to set aside Hollywood histrionics and try to help with the problem instead of this baseless, and tasteless, finger pointing," Fratto told the New York Times.

David said that she was shocked by Rove's response.

"I honestly thought that I was going to change his mind, like, right there and then," she told the Associated Press.

Earlier this month, Crow and David embarked on their Stop Global Warming College Tour, riding a biodiesel bus to 12 campuses across the U.S. in an effort to increase student awareness of the issues surrounding climate change.

The tour concluded at George Washington University Sunday, coinciding with Earth Day. In addition to Crow, Carole King, Tim McGraw and Faith Hill performed, while David's husband, Seinfeld creator and Curb Your Enthusiasm star Larry David spoke, along with Robert F. Kennedy Jr.

Crow dedicated the closing song of the concert, a cover of the Beatle's "We Can Work It Out," to Rove, who she referred to as "my new friend."