Until this week. After taking last week off the campaign trail -- totally unheard of for a candidate in the midst of a contested primary fight -- Trump needed this week to be a momentum-builder before Tuesday's winner-take-most Wisconsin primary. It has been the exact opposite.
The week began with the news that Corey Lewandowski, Trump's high-profile and controversial campaign manager, had been charged with battery for grabbing Breitbart News reporter Michelle Fields after a Trump event earlier this month. Not only did Trump refuse to fire Lewandowski, who had previously insisted that he had never touched Fields, but the Republican front-runner also mounted an aggressive attack against the reporter -- insisting that she had changed her story, exaggerated badly and actually, wait for it, had been a threat to him.
So, that was bad. But it would get much worse.
Trump's fumbling answers on abortion during a town hall event with MSNBC's Chris Matthews on Wednesday led to a series of clarifications and revisions of what, exactly, his position is on the issue. Trump initially suggested that if abortion were made illegal, there would need to be punishment for women who had abortions. Then, in a statement, he said that the issue is best left to the states. Then, in a follow-up to the first statement, Trump said he thinks that women should not be punished for seeking an abortion but that the blame should rest with the health-care provider who performed the procedure. Got all that?
The story of what Trump said about abortion (and what he meant to say) will dominate the coverage for at least the next 24 hours. That brings us to Friday in a week in which not one second of the coverage was positive for Trump -- and all of it was the result of self-inflicted wounds.
Having such a bad week matters more now than ever because Wisconsin's primary is just days off. Wisconsin is one of a handful of states left on the calendar where Trump could take the lion's share of delegates if he wins statewide. And, to get to the 1,237 delegates he needs to formally clinch the party's nomination before the national convention in July, he needs strong showings in states such as Wisconsin.
The problem is that even before this disastrous week, polling in the state suggested that Trump wasn't going to get the win he wanted/needed. A poll by Marquette Law School in Milwaukee released Wednesday showed GOP rival Ted Cruz running first, with 40 percent. Trump took 30 percent, while John Kasich was at 21 percent. The poll also found that 70 percent of Wisconsin voters have an unfavorable opinion of Trump.
If Trump loses statewide in Wisconsin on Tuesday, he might still be able to claim some delegates from the state, because the winner in each of the eight congressional districts will win three delegates. The problem for Trump is that Wisconsin was a state in which, as recently as a month ago, it looked as though he might be able to take all 42 delegates for himself.
Losing Wisconsin wouldn't zero out Trump's chances of getting to 1,237. But it make the odds far longer than if he were to win convincingly. To put it simply: Losing Wisconsin would erase any margin of error for Trump in the states still waiting to vote.
Of course, up has been down and right left for Trump this entire campaign. He has committed seemingly campaign-ending gaffes more times than I can count only to watch his poll numbers increase in their wake. It's possible then that this is yet another one of those moments -- and that he will soar to victory in Wisconsin on Tuesday.
But I doubt it. This week looks and feels like a gigantic momentum-killer for Trump at a time when he can least afford it.