Paper props are apparently the weapon of choice in a spat between White House Press Secretary Robert Gibbs and GOP operative Karl Rove.

Waving a blank piece of paper to illustrate his point during a briefing with reporters on Tuesday, Gibbs said the president does not have an enemies list, as Rove has charged.

Rove's Wednesday comeback included three times as many paper props. Appearing on Fox News, where the former George W. Bush adviser is also a contributor, Rove held up a piece of paper that read, "White House credibility" and the word "NONE." And he had additional props. "In fact, you know, while we're at it, let's talk about the president's evidence for the accusation that the Chamber of Commerce and American Crossroads had foreign donors," said Rove as he held up another paper reading "Obama's Evidence" and the word "NADA."

During Tuesday's off-camera briefing with reporters Gibbs asked to see the donors to American Crossroads, referring to Rove's group.

Rove's direct answer included -- more paper. "I'm happy to respond to Mr. Gibbs's request for a list of the foreign contributors to American Crossroads," Rove said holding up a paper that read, "Crossroad's Foreign Donors" with the number zero below it.

"None. None," said Rove.

The White House has been attacking the group Rove advises, American Crossroads, along with the U.S. Chamber of Commerce, saying that they should reveal who is funding their operations. Both groups have fought back saying that there are plenty of Democratic groups who don't expose their funding.

Critics also say the White House's argument is a non-argument since they're saying the groups could have overseas donations and need to prove they don't, but not actually providing concrete examples of the alleged contributions.