Donald Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE is again raising the possibility that he might run for president as a third-party candidate, suggesting that the Republican Party is not meeting its end of their loyalty "deal".

Responding to reports that independent super-PACs are planning attack ads against his candidacy, the billionaire Republican front-runner tweeted on Monday:

.@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

Asked what "reports" Trump was referring to, his campaign manager Corey Lewandowski said in a telephone interview that it was a reference to plans by a super-PAC supporting Ohio Gov. John Kasich to run a $2.5 million campaign against Trump

Trump's tweet excavates a problem that the Republican National Committee (RNC) thought it had buried three months ago.

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RNC Chairman Reince Priebus convinced Trump to sign a loyalty pledge that he would support the party's eventual nominee, and when the front-runner did so, on Sep. 3, the party thought the issue was over.

Trump said at the time: "I see no circumstances in which I would tear up that pledge."

Asked what Trump meant by his tweet Monday, Lewandowski said: "He wants to be treated fairly."

"But if Republicans are going to go attack him then maybe he doesn't think he's being treated fairly," he added.

Lewandowski did not explain how Trump is equating the super-PAC's plans to being treated fairly by the national committee, which has nothing to do with the spending.

It is the second time in two days that Trump has publicly toyed with abandoning the pledge and running as an independent.

Interviewing Trump on ABC's "This Week" program Sunday, host George Stephanopoulos asked the businessman whether he would launch a third-party bid amid news that GOP operatives are planning to launch an anti-Trump “guerilla campaign.” “You know, when I did this, I said I have to be treated fairly,” Trump told Stephanopoulos. “If I’m treated fairly, I’m fine. All I want to do is a level playing field.”

Trump first raised the possibility of a third-party candidacy in an exclusive interview with The Hill in July , saying the RNC “has not been supportive.” Pressed on whether he would run as a third-party candidate if he fails to clinch the GOP nomination, Trump told The Hill that “so many people want me to, if I don’t win.”

Bradford Richardson contributed reporting.