McConnell, speaking during a weekly press conference, said that an impeachment trial in the Senate would not begin before the upper chamber wraps up its work for the year, which it is expected to do next week.
"What is not possible, obviously, would be to turn to an impeachment trial or to do USMCA in the Senate before we break for Christmas," McConnell said, referring to Trump's newly renegotiated trade deal with Canada and Mexico.
McConnell's comments come after House Democrats formally unveiled articles of impeachment earlier Tuesday. The House Judiciary Committee is expected to start voting on the articles on Wednesday night and continue into Thursday.
A full vote on the House floor is expected as soon as next week.
Senators have predicted for weeks that the upper chamber would bypass holding impeachment proceedings before the end of the year and would instead start the trial in January.
During the Clinton impeachment, the House passed articles of impeachment in mid-December but the Senate did not start its trial until the first week of January.
He added that a trial would "be a sometime January exercise."
McConnell sidestepped saying on Tuesday when the Senate would return to Washington in January. The chamber's 2020 calendar was released last week, but the month of January was missing from the calendar — underscoring the scheduling uncertainty.
"We will let you have a date as soon as we have it, but you know it will be — it will be — you are wondering when you have to come back, right? It will be — it will be right around the time the bowl games end. So how about that?" he said.