CNN says 4 GOP senators have committed in the past not to vote for a nominee during an election. I expect most if not all of them to break their word.
Here is a list of four Republicans senators who have said they will oppose a vote before the election:
Maine Sen. Susan Collins told the New York Times, “I think that’s too close, I really do."
Alaska Sen. Lisa Murkowski in September said, "Fair is fair," and she would not vote to replace RBG before the election."
South Carolina Sen. Lindsey Graham in October 2018 said, "If an opening comes in the last year of President Trump's term, and the primary process has started, we'll wait to the next election. And I've got a pretty good chance of being the Judiciary [Chairman]. Hold the tape."
Iowa Sen. Chuck Grassley said in July he would follow the Biden rule, "I'm just following what was established by the Biden Rule in 1986 and then emphasized by him in 1992... They set the pattern. I didn't set the pattern. But it was very legitimate that you can't have one rule for Democratic presidents and another rule for Republican presidents."