McConnell said in a tweet on Thursday that the transition after the presidential election in November will be "orderly" and whoever wins the vote will be inaugurated on January 20, 2021.
McConnell's comments come after President Donald Trump a day earlier during a press conference refused to say whether he would hand over power if he loses the vote.
Asked earlier whether he would guarantee a peaceful transfer after the election, Trump responded "We’re going to have to see what happens."
Trump has repeatedly claimed that widespread mail-in voting due to the coronavirus pandemic could result significant fraud. Democrats say the claim is unfounded.