With Washington insiders trading barbs over former counterterrorism adviser Richard Clarke's (search) scathing criticism of the Bush administration, the national director of Win Without War (search), a group devoted to ousting President Bush, accused the White House of character assassination.

Director Tom Andrews said Wednesday that the president should be focusing on the substance of the Clarke critique rather than attacking the man who served as his counterterrorism coordinator and special adviser on cyberspace security.

"I can understand the president's desire to change the subject. For two years former U.S. intelligence officials and counterterrorism experts have argued two points: that President Bush misled the nation by falsely linking 9/11 with Saddam Hussein; and that he has made Americans less safe by invading Iraq thereby fueling terrorism, alienating key allies, and diverting resources from the real enemy, Al Qaeda," Andrews said.

"Now's the time to admit error and change course so that Americans can be safer. Politics should come second to that," he added.

Meanwhile, presumptive Democratic presidential nominee John Kerry (search) bemoaned the end of his ski vacation while avoiding questions over the dust-up.

"I don't know anything about it," said Kerry, questioned by reporters as he arrived at the ski slopes. "It's my last hours, my last hours," the Massachusetts senator said.

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In a new book, Clarke contends that the White House didn't respond to warnings of potential terrorist attacks and manipulated the nation into a war with Iraq. The White House has moved aggressively to discredit Clarke, sparking complaints that the administration is focused solely on avoiding political fallout.

Kerry had previously declined to wade into that disagreement. He said he's asked to have a copy of Clarke's book shipped to his vacation home so he can study it before commenting.

During his nearly weeklong vacation at an upscale ski resort in Idaho, Kerry has had little to say publicly even as the Bush campaign stepped up its criticism of Kerry on the stump and in new attack ads.

Kerry planned to return to Washington on Wednesday night. Aides have said the Massachusetts senator needed a low-key vacation after emerging victorious from an intense primary campaign.

However, the pace is about to change dramatically. Kerry hits the campaign trail running on Thursday, meeting with Democratic National Committee (search) officials to coordinate campaign efforts and stumping with former rival Howard Dean (search). He's also scheduled to attend a unity dinner featuring former presidents Carter and Clinton before flying to key battleground states of Michigan and Missouri.

Campaign aides, meanwhile, blamed miscommunication for Kerry missing a "thank you" gathering at a tavern for about 100 local volunteers who served as guides and drivers for reporters and others on his campaign.

"We're sorry for any misunderstanding. It wasn't something that the campaign committed to doing," spokeswoman Laura Kapps said. "He is extremely grateful for the graciousness of the people of Ketchum, and I'm sure he's planning to thank those folks as he prepares to leave."

Fox News' Peter Brownfeld and The Associated Press contributed to this story.