Whiting confirmed in an e-mail that his boss “intends to resign on Sept. 30th. However, he is fighting these charges, and should he be cleared before then, he may, and I emphasize may, not resign.”

Craig’s move stunned even supporters. Most political insiders believed Craig had finally gotten the message from national Republican leaders, who saw his guilty plea to a humiliating sex-related charge as a blemish on the party’s reputation and its prospects for the 2008 election.

"We didn't know anything about this," said a spokesman for Idaho Gov. Butch Otter, who stood with Craig during the resignation announcement. Otter, a congressman until his election as governor last fall, will pick Craig’s successor. Craig’s hedging may play poorly even among Idaho supporters who believe Craig was railroaded, observers said.

"I'm not sure how Idahoans will take it if they feel like they were misled by his statement on Saturday," said Jim Weatherby, a retired political scientist at Boise State University. "He was playing a word game, apparently, with us."

A senior GOP Senate strategist said Republican leaders want him gone now and will press for him to keep his promise to resign. The strategist warned Craig is "losing any goodwill built up among his colleagues," adding, "He is simply a fish out of water, floundering right now to get his last gasp of political air."

"It simply defies reality," said a Senate GOP aide. "You can't make this up even if you are heavily medicated. The American people heard from Larry Craig that he would resign, and using the word 'intent' as a back door doesn't work with them."