That's what the five lawmakers who came forward with the ethics complaint against Walker are now considering, according to their legal counsel, David Irvine. "We're still exploring options and there are several," Irvine said.

The ethics complaint states that Walker "offered to use his position as a legislator and his legislative connection with an unnamed member of the legislative body to secure a legislative appropriation in order to bribe another government official," Ellis.

Ellis had stated in his original elections complaint, filed with Lt. Gov. Gary Herbert, that Walker assured him he could make the pay raise "happen and that he had talked with 'the person' who could make it happen."

Irvine said he was "not 100 percent sure" the person referred to was Curtis. But, Irvine said, the House speaker certainly was among the handful of GOP leaders able to make such a commitment.

He also suggested Walker was forced out, presumably to stop the investigation. "It's pretty clear that the House leadership has made a decision to sacrifice, in chess terms, a pawn to save the king," Irvine said.

The House speaker was upset at the suggestion he may be the target of a new ethics complaint. "I refuse to comment on these unfounded, mean-spirited, politically motivated accusations," Curtis said.

As for Walker's decision to step down, Curtis said he was "disappointed Mark felt it was was necessary to resign, but he determined that it was in his own best interests for himself and his family to put this matter behind him and move forward."

Walker, 32, first elected to the Legislature in 2004, is expected to be replaced by the GOP candidate for his seat, Brian Monsen. Monsen's Democratic opponent, Laura Black, lost to Walker two years ago by just 18 votes.

Walker did not return telephone calls Monday and his voice mail referred callers to his attorney. His campaign manager, Steve Hunter, said Walker and his family planned to spent the next few weeks with his family, including his pregnant wife, at a secluded cabin.

Hunter said he talked with Walker on Sunday about his decision. "He just said, 'I just can't do this to my family anymore. I know I should stay and fight and get the story about Richard and everything out there,'" Hunter said.

Walker considered how his resignation would be seen, Hunter said. "He feels like if he resigns, everyone is going to say he's covering the unnamed legislator," Hunter said. "There's no one to cover for. There's no one there."

Walker said in his letter of resignation that he will fully participate with the Davis and Weber county attorneys named by the attorney general to handle the criminal investigation into what would be a class B misdemeanor.