Donald Trump has until Sept. 30 to pledge to rule out a third-party run if he intends to appear on the South Carolina primary ballot.

“I hereby affirm that I generally believe in and intend to support the nominees and platform of the Republican Party in the November 8, 2016 general election,” reads the state’s 2016 presidential primary filing form, which was sent to the campaigns in June.

Trump, the billionaire businessman and reality television star, has repeatedly refused to rule out a third party run if he fails to become the eventual Republican nominee. Many believe that would all-but-guarantee a win for Democrats in the general election.

While Trump says he’d prefer and intends to run as a Republican — as long as he’s treated fairly. He has said the threat gives him leverage against a party establishment that has been rattled by his unconventional campaign’s summer surge.

Other states are considering adding similar language, in an apparent attempt to force Trump’s hand.

But state Republican Party Chairman Matt Moore said the language, which is new, was not related to Trump’s candidacy and was added to make the form consistent with pledges signed by candidates running at the state and local levels.

Four years ago, the form read: “I hereby affirm that I generally believe in and intend to support the concepts found in the principles and policies of the Republican Party in the upcoming election.”

“We’ve had this kind of language in South Carolina for decades so I see nothing wrong with it,” said Moore.

“It’s about protecting the integrity of the ballot” so that candidates get only “one bite at the apple,” he said.

A spokeswoman for Trump’s campaign did not immediately respond to a request for comment.

But Moore said the party has been in communication with his campaign team over the past few weeks and that “the pledge has not been an issue.”

The Virginia and North Carolina Republican parties are also currently in discussion about adding similar pledges to their filing forms, Politico reported Monday.

Virginia Republican Party Chairman John Whitbeck said the prospect of adding the pledge, which will be decided by the state party’s central committee at a meeting on Sept. 19, had nothing to do with Trump.

“It’s about unifying the party,” he said. “We want people who compete in our primaries and our nominating process to be committed to supporting the nominee,” he said.

North Carolina GOP Chairman Hasan Harnett also pushed back, saying the party “has no intention of restricting or preventing any legitimate Republican candidate from running” in the state.

“The press is trying to create a story by reporting rumors and hearsay,” he said in a statement, citing a state law that would already bar Trump or any Republican presidential primary candidate from running on any other party’s line in the general election.

Former Trump adviser Roger Stone, who recently parted ways with the campaign, said on Twitter that the Virginia and North Carolina moves are “the kind of thing that could make @realDonaldTrump bolt the GOP and run third party or Indy.”

(AP)