Ms. Collins said in an interview on Sunday night that she considered the allegations serious and that Ms. Ford needed to be personally interviewed to get a fuller account. But Ms. Collins, who could conceivably decide the outcome in the narrowly divided Senate, said Democrats had done a disservice to both Ms. Ford and Judge Kavanaugh with their handling of the accusations.

“What is puzzling to me is the Democrats, by not bringing this out earlier, after having had this information for more than six weeks, have managed to cast a cloud of doubt on both the professor and the judge,” she said. “If they believed Professor Ford, why didn’t they surface this information earlier so that he could be questioned about it? And if they didn’t believe her and chose to withhold the information, why did they decide at the 11th hour to release it? It is really not fair to either of them the way it is was handled.”