Republican officials say Gov. Butch Otter will name Lt. Gov. Jim Risch to the Senate if Sen. Larry Craig resigns.
But Otter's spokesman Jon Hanian said the governor hasn't made that decision yet.
"The governor has made no promises or guarantees to anyone regarding a seat that at this hour is still occupied by Larry Craig," Hanian said. "We have not heard anything otherwise from their office."
"We'll deal with the facts when we know them," Hanian added.
Hanian said Otter and Craig had spoken on the phone in the past few days, but Otter spent most of Thursday on his previously scheduled business.
Craig is considering resigning, Republican officials said this morning, after days of public and private pressure stemming from his arrest in June in a police undercover operation at an airport mens room.
Risch served for seven months as governor last year after former Gov. Dirk Kempthorne was named Interior Secretary. Risch had said earlier he was interested in Craigs Senate seat if Craig did not seek re-election in 2008.
Rep. Mike Simpson, R-Idaho, also has been mentioned as a possible replacement for Craig, but the officials, speaking on condition of anonymity, because Craig has not resigned, told the Associated Press Otter would choose Risch.
If Craig leaves, Idaho Democrats are calling on Otter to choose someone just to fill out the remaining year of Craig's term.
"He shouldn't make this decision a political one," said Chuck Oxley, the state party's spokesman. "He should find an unimpeachable experienced statesman who can fill out the term and let the people of Idaho choose who the next senator is."
Senate Minority Leader Mitch McConnell today called Craigs conduct unforgivable and acknowledged that many in his caucus believe Craig should resign.
We have acted promptly to begin the process of dealing with this conduct, McConnell said. We will see what happens in the coming days.
Craig pleaded guilty to disorderly conduct on Aug. 1, and while he has since said he did nothing wrong, the episode has roiled the Republican party and produced numerous calls for him to step down.
The statement from McConnell was among the strongest yet from GOP leaders, who have pressured Craig for days.
As a measure of the pressure Craig faces, party officials said a statement had been drafted at Republican Party headquarters calling for the third-term senator to resign. It was not issued, these officials said, in response to concerns that it might complicate quiet efforts under way to persuade the 62-year-old lawmaker to give up his seat.
Craig has not made any public statements about his case since an appearance earlier this week in Boise, in which he said he had done nothing wrong. I am not gay. I never have been gay, he added emphatically.
He said any additional comment would be posted on his official Web site, where the only reference to the incident as of Friday morning was a text of the statement he read before the television cameras.
Craig, 62, served in the House before winning his first Senate term in 1990, and compiled a strongly conservative voting record.
He was arrested on June 11 by an undercover police officer in a Minneapolis airport mens room who said the senator had engaged in conduct often used by persons communicating a desire to engage in sexual conduct.
Minutes after he was arrested for lewd conduct, Craig denied soliciting for sex, saying Im not gay. I dont do these kinds of things, according to an audio tape released by police on Thursday.
He denied that he had used foot and hand gestures to signal interest in a sexual encounter. The officer, Sgt. Dave Karsnia, accused the three-term senator of lying and grew exasperated with his denials.
Embarrassing, embarrassing. No wonder why were going down the tubes, Karsnia said.
In the police interview, Craig, 62, never admitted doing anything wrong and said his actions had been misinterpreted. However, Karsnia wrote in his report that the gestures were consistent with efforts to find a sexual partner in the mens room.
Craig later pleaded guilty to a reduced charge of disorderly conduct, which he now calls a mistake. More Republicans distanced themselves from Craig on Thursday. Sen. John Ensign of Nevada, who chairs the GOPs senatorial campaign committee, stopped short of calling on him to resign but suggested strongly that he should.
I wouldnt put myself hopefully in that kind of position, but if I was in a position like that, thats what I would do, Ensign told The Associated Press in his home state. Hes going to have to answer that for himself.
The partys Senate leadership had previously called for the ethics committee to investigate, and on Wednesday took the highly unusual measure of asking him to give up his seniority in committee positions. Craig complied.
On the tape, Craig and the arresting officer can be heard arguing over what happened in the mens room minutes earlier. Craig acknowledges that the mens feet bumped but says nothing improper happened.
Did we bump? Yes, I think we did. You said so. I dont disagree with that, Craig said.
But Craig disputes the officers account that he swept his hand under the stall next to him in an apparent effort to advance the encounter. They even disagree whether Craig used his right hand or his left hand.
Craig said he was merely trying to pick up a piece of paper an account the officer disputes. Im telling you that I could see, so I know thats your left hand. Also I could see a gold ring on this finger, so thats obvious it was the left hand, Karsnia tells Craig.
Well we can dispute that, Craig says. Im not going to fight you in court. I reached down with my right hand to pick up the paper.
Karsnia said in a police report that there was no paper on the floor and he recognized Craigs hand gesture as a signal aimed at initiating sex.
Associated Press writers Scott Sonner in Reno, Nev., Joshua Freed in Minneapolis, John Miller and Todd Dvorak in Idaho and Liz Sidoti in Washington contributed to this report.