"Already, Republican Sens. Lisa Murkowski of Alaska and Susan Collins of Maine have said that there is not enough time to confirm someone before November. Collins told The New York Times earlier this month that she'd oppose seating a nominee in a lame-duck session if Joe Biden wins the White House."[1]
So a fairly razor thin opportunity for McConnell.
[1] https://www.cnn.com/2020/09/18/politics/congress-fight-rgb-s...
They're not going to turn that down just to mess with Trump, this is way bigger than Trump.
https://www.pewresearch.org/fact-tank/2020/08/24/trumps-appr...
Also see: The most recent RNC.
I assume that is well below the percentage of Americans that call themselves Republican. Not fully understanding your point. The language in your link seems to confirm it's a serious issue for Trump.