"There is no limit to the amount of good you can do," Ronald Reagan said, "if you don't care who gets the credit."
Replace "good" with "stuff," and you've got the current situation vis a vis "COVID-19 relief."
Politicians on both sides of the partisan aisle care a great deal about who gets credit for shoveling a bunch of money at a bunch of voters (and campaign contributors, and powerful special interests), right before an election in which the White House and control of the Senate look to be very much up in the air.
Neither side wants the other side to be able to use the issue to knock down those last few undecided votes.
After July or so, there was never likely to be a pre-election "COVID-19 relief" deal.
But by cutting off negotiations that were never going to get anywhere, instead of letting those talks continue, Trump just publicly positioned himself, and only himself, as responsible for the impasse.
He's using it as a rallying cry/Get Out The Vote pitch for his base -- "I have instructed my representatives to stop negotiating until after the election when, immediately after I win, we will pass a major Stimulus Bill that focuses on hardworking Americans and Small Business" -- but his base was already as solid and enthused as it was going to get.
If there's any chance for him to win this race, that chance rests with whatever "undecided" voters are left.
And he just told those voters that he's the one holding their expected "COVID-19 relief" money hostage for the next month.