Of much more importance is the difference between them on the war with Russia. If Trump had the courage to oppose Biden on that expenditure, he would almost certainly create a winning issue for himself.
The only holdback is in Trump convincing his following that it's time to take an antiwar position.
That's a new concept for the political right to interfere in the progress of a war, but this war is the exception to all the previous US wars in that it's unwinnable. Russia will go nuclear before they lose.
Trump could capitalize on an antiwar position immediately, and revers his flagging popularity decline.