Donald Trump's landslide loss in the Wisconsin primary has brought a glimmer of hope to outside groups who've spent months and millions of dollars trying to derail his candidacy.

Now, the Republican presidential front-runner's deep-pocketed opponents have a burning desire to do more damage.

Shortly after Texas Sen. Ted Cruz was projected to win in Wisconsin on Tuesday night, a group that has led the charge against Trump since its inception in mid-January released a statement promising to siphon off as many delegates as possible from Trump in the likely event that Republicans have a contested party convention.

"[We] will wage an aggressive fight for every delegate vote in the coming weeks to ensure the GOP wins the White House this fall with a principled, conservative standard bearer," said Katie Packer, a former aide to Mitt Romney and founder of Our Principles PAC.

Packer's group spent $2 million to saturate Wisconsin airwaves with anti-Trump attack ads in the weeks leading up to the state's nominating contest. OPP also contacted more than 1 million Wisconsinites by mail, email or phone to discuss Trump's mixed record on conservative issues, and reached out to convention attendees who've been "advocating for a slate of 'non-Trump' delegates."

We're really focused on how to peel away the numbers he needs to get to the 1,237 [delegate count needed to secure the nomination]," Packer told the Washington Examiner.

"Indiana is a state we're looking at and we think we have an opportunity to peel away some of the delegates he needs there," she added.

Packer says OPP was "very active" in the recent delegate battle in North Dakota, where the Cruz campaign claimed it 18 of the state's 25 delegates are supporters of the Texas senator. "We are currently active in Colorado and are trying to ensure that the people who win these delegate slots are people who are not going to support Trump."

"We're really trying to get people who understand the threat Trump represents, and even if they're bound on the first ballot, might vote against him in subsequent rounds," Packer explained.

While Packer's group transitions its focus to the behind-the-scenes delegate battle, the conservative super PAC Club for Growth Action plans to continue hitting Trump with negative attack ads in several of the remaining states.

The Club's president, David McIntosh, described Wisconsin as "the beginning of the end for Trump," and he plans to stick around until he's finished.

"What Wisconsin shows you is the tremendous concern about Trump — that voters comfortable with any of the candidates did not stick with their favorite, but they instead voted strategically," McIntosh told the Washington Examiner.

Much like OPP, McIntosh's group took to the airwaves with a seven-figure ad campaign ahead of the Wisconsin primary to convince voters that Trump would be a ticking time bomb as the Republican nominee, and that voting for Cruz is the best way to stop him.

The Club is now looking ahead to New York, where McIntosh hopes to spin Trump's anticipated victory as a loss.

"In New York, the key strategy for us at this point and all the 'Stop Trump' groups should be to make sure he does not get 50 percent," McIntosh said, noting that the Club will get involved in the Empire State if polls suggest Trump could reach that threshold.

"That would be a win for Trump and show that he could recover and be the comeback kid," he said. "But if he gets less than 50 percent in his home state, it really would be another loss considering he would lose about a third of the delegates and we're in a delegate race now."

After New York, the group will focus its attention on states like Maryland and Indiana, which have produced limited public polling and where the voting terrain could prove more favorable to Trump's opponents.

"I think what the strategy will continue to be is a combination of what occurred in Wisconsin," McIntosh said. "We started with telling voters that Trump is really not a conservative and they started to become aware that he'd lose badly to Hillary [Clinton]."