And on Saturday night, he got the ball rolling.
Trump, facing a GOP exodus from his campaign and apparently desperate to change the subject, just retweeted two tweets from an account featuring the name of Juanita Broaddrick, the woman who publicly alleged in 1999 that Clinton had sexually assaulted her two decades prior. Clinton has long denied the accusation.
In both tweets, the Broaddrick account reiterates her accusation that Clinton raped her and accuses Hillary Clinton of enabling him.
Trump has yet to make these accusations a big part of his campaign, but he made clear in his statements after Friday's explosive video that he was preparing to go there.
“Bill Clinton has said far worse to me on the golf course — not even close,” he said in his initial comment as the story was posted. “I apologize if anyone was offended."
Then, in his fuller apology late Friday night: "I've said some foolish things, but there's a big difference between the words and actions of other people. Bill Clinton has actually abused women, and Hillary has bullied, attacked, shamed and intimidated his victims. We will discuss this more in the coming days. See you at the debate on Sunday."
These, mind you, were prepared statements from his campaign. And given the discord over what has transpired over the past 30 hours, it's not clear from whom Trump is taking direction or if he's even listening to anyone not named Donald Trump.
One Trump adviser who appears to be urging the Bill Clinton attack is Roger Stone, a controversial figure who told The Washington Post on Saturday that he had teamed with the conspiracy theory website InfoWars to sell 10,000 T-shirts with Bill Clinton's face next to the word “rape" — a la Barack Obama's "hope" poster.
Here's what we can say at this juncture:
First, the GOP has basically turned this into Trump, Unplugged. The party largely played nice with Trump after he secured the Republican nomination, hoping that it could at the very least prevail upon him to run a semi-serious campaign that doesn't ruin things for all those other Republicans whose names will appear below Trump's on the ballot.
Republicans might not have actually thought Trump would win, but they needed him to stay competitive. And to do that, it helped to at least have a seat at the table. It's not that Trump was ever particularly good at taking direction from the GOP establishment, but now that much of the Republican Party is cutting bait and calling for him to drop out, he's liable to do whatever he wants.
Second, Trump isn't going without a fight. Other candidates might have done some real soul-searching after their party disowned them en masse and basically gave up on them having any chance to win. The odds against Trump appear longer than ever — without any polling to back that up, of course — but he's clearly not reevaluating himself or his approach. He's quadrupling down.
Trump clearly doesn't view the rest of this campaign as an attempt to salvage his good name or to quietly fade away; he views it as a war in which he's not going to unilaterally disarm when it comes to Bill Clinton.
And lastly, it shows that we might be embarked upon one of the nastiest, angriest and most passionate moments in presidential campaign history. The prospect of Trump unleashing a torrent of attacks on Bill Clinton — or even labeling him a rapist, as the Broaddrick account does — is hard to compare to anything we've seen in recent political history.
There is much about Trump's campaign that is unprecedented, but the idea that this would come to be a feature of the 2016 campaign is just remarkable.
Retweets may not be endorsements, but Trump clearly just endorsed a race to the bottom.