Trump has 85 college votes in states where he's 10% or more ahead.
Another 35 leading by 5-10 points.
And another 41 where he's edging ahead between 0 and 5 points.

Giving a total of 161 of the 270 needed.

So if Trump wind everything where he's ahead even by a fraction, he comes up 109 college votes short.

So then he has to eat into Biden's staes

So to start with Trump has to take all the states where Biden is nudging ahead by 0-5 points.
That gives him another 78 college votes to a total of 239 of the 270 needed to win.

So Trump has to win 31 college votes from states where Biden is leading by 5-10 points, which are:

Pennsylvania (20 college votes)
Michigan (16)
Minnesota (10)
Wisconsin (10)
Nevada (6)

Which means Trump winning every state where he's got even the smallest lead.
And winning every state where Biden is edging a lead
And winning at least two states where Biden is 5-10 points clear

And every state that Trump fails to win where Biden is just in front means Trump will have to make those numbers up from states which are progressively harder to win.

What's going to kill Trump is the core vote. States with a 10 point lead that are as safe as a state can possibly be.

Biden: 19 states, 214 college votes

Trump: 14 states, 85 college votes

And if you add up the core states plus those with a comfortable lead of 5-10 points, you get

Trump: 19 states, 120 college votes

Biden: 24 states, 278 college votes

Trump has to win all these states where Biden is ahead

North Carolina
Arizona
Florida
Georgia
Iowa
Pennsylvania
Michigan

And if he loses any one of them he'll lose the election