The campaign managers for President Bush (search) and Democratic rival John Kerry (search) exchanged dueling letters Tuesday demanding the release of potentially embarrassing material.

Bush campaign manager Ken Mehlman repeated his request that the Kerry campaign release a tape of a concert fund-raiser last week in New York City. Some performers referred to the president as a thug and a liar, and Kerry later praised the celebrities who had appeared.

Mehlman promised his campaign would not use the performance in campaign advertising.

Kerry campaign manager Mary Beth Cahill responded with her own letter, saying the Bush campaign's "paparazzi-like obsession" with the fund-raiser is misplaced when the public is more interested in seeing documents relating to the president's service in the military and the White House.

Cahill said the Kerry campaign would not consider releasing the fund-raiser until Bush releases proof that he fulfilled his National Guard duty and government documents relating to the no-bid contracts awarded to Halliburton Co., the drafting of the energy and Medicare bills, and the prison abuse scandal in Iraq.