And while anti-Trump forces have ramped up their attacks in recent weeks as the prospect of a Trump nomination has gotten more and more likely, Trump has largely continued his string of primary and caucus victories.
“The situation is fluid regarding how these stop Trump campaigns will move forward,” a source close to the anti-Trump efforts told ABC News. “Decisions will be made over the coming days as to the best use of resources: continue a public advertising campaign to further expose Trump’s record and slow his primary momentum or work on a delegate strategy at the GOP convention.”
Anti-Trump ad spending accounted for only one in six Republican ad spending dollars in the week before and after Trump won the New Hampshire primary. But in just the first three days of this week, anti-Trump forces have doled out a whopping $7.6 million – making up two in every three GOP ad dollars spent.
This means anti-Trump advertising increased 900 percent between the first two weeks in February and the days before the crucial March 15 contests in Florida and Ohio.
“Nobody has ever, ever in the history of politics received the kind of negative advertising that I have,” Trump claimed after his Florida victory on Tuesday. “By the way, mostly false, I wouldn't say 100 percent, but about 90 percent. Mostly false, vicious, horrible.”
But now, with its two biggest players sidelined, the anti-Trump movement is spearheaded by other super PACs that have committed to blocking Trump from reaching a majority of delegates before the convention, including Our Principles PAC and the economically conservative super PAC Club for Growth Action.
“The Club and its super PAC are evaluating the other remaining states and we plan to continue efforts,” said Doug Sachtleben, spokesperson for Club for Growth Action, which just announced a new anti-Trump ad airing in Utah.
“We believe it's entirely possible to keep Trump under 1,237 and to see Cruz amass a significant chunk of delegates,” he told ABC News.
But despite the onslaught of negative advertising in recent weeks, Trump has a viable path to clinching the nomination if he can chalk up victories in upcoming big states like Arizona, New York and California.
“And you explain it to me because I can't,” Trump said on Tuesday night. “My numbers went up. I don't understand it. Nobody understands it.”