After Collins, Romney and Murkowski, there is a larger group of GOP senators who have publicly or privately expressed concern over Trump’s withholding of military aid to Ukraine and his attempt to persuade Ukrainian President Volodymyr Zelensky to conduct a corruption investigation.

The group includes GOP lawmakers such as Sens. Rob Portman (Ohio), Ron Johnson (Wis.), Tim Scott (S.C.), Marco Rubio (Fla.), and Lamar Alexander (Tenn.), who is not seeking reelection.

But none of them are seen as being close to voting for any articles of impeachment, barring a major revelation of new information, say Senate GOP aides.

A senior Senate GOP aide said Collins, Romney and Murkowski are the only possible defectors “and the list ends there” unless dramatically new information emerges before a vote.