An aide to Republican presidential candidate Donald Trump said Tuesday that the Republican National Committee should defend Trump against a new attempt to take down the businessman’s bid for the presidency—or else face the consequences.

The Wall Street Journal reported last week that a new, Republican-backed effort was underway to take down Trump. The initiative, led by former RNC operative Liz Mair, was described as “loosely organized and highly confidential.”

Michael Cohen, executive vice president and general counsel at the Trump organization, questioned Tuesday on CNN’s “New Day” whether Mair’s group was an RNC-supported effort. He added that it was a “bad, bad decision” to come after Trump.

“Donald Trump wants to be treated fairly. He will demand that the GOP treat him fairly,” Cohen said. “If they treat him fairly, he will honor the pledge cuz he’s an honorable guy. If they break that agreement with him, as they say, ‘woe be on them.'”

The real estate mogul generated headlines this summer for refusing to rule out a third party bid for the presidency, but signed a pledge to run as a Republican at the beginning of September. Cohen suggested that promise might be in jeopardy if the RNC was behind the effort to derail Trump’s campaign.

“Reince Priebus has an obligation to Donald Trump in order to treat him fairly, make sure the process treats him fairly and if they don’t—this will be a very, very bad thing for the Republican party,” Cohen said.

Here’s what Trump tweeted Monday about Mair’s group:

.@WSJ reports that @GOP getting ready to treat me unfairly—big spending planned against me. That wasn’t the deal! — Donald J. Trump (@realDonaldTrump) November 23, 2015

He also took a personal shot at Mair in a Saturday tweet:

A woman who got fired after two days of working with Scott Walker – a wacko – now trying to raise funds to fight me. — Donald J. Trump (@realDonaldTrump) November 21, 2015

Notably, Trump again refused to rule out a third party bid Sunday during an interview with ABC’s “This Week.”

“I’m going to have to see what happens,” Trump said. “I will see what happens. I have to be treated fairly.”