Donald TrumpDonald John TrumpFive landmark moments of testimony to Congress Lindsey Graham basks in the impeachment spotlight Democrats sharpen their message on impeachment MORE is still flirting with a third-party campaign days after meeting with the chair of the RNC.

"It's not that simple," Trump said in an interview on "Fox News Sunday" when asked if he would rule out a third-party run. "I’m by far the front-runner as a Republican. I want to run as a Republican. I will beat Hillary ClintonHillary Diane Rodham ClintonFive landmark moments of testimony to Congress Top diplomat said request for specific probes in Ukraine was 'contrary' to US policy Feehery: What Republicans must do to adapt to political realignment MORE."

When host Chris Wallace asked what he would do if he didn't get the nomination, Trump responded: "We’re going to have to see how I was treated. I'm going to have to see how I was treated, very simple."

Trump has previously toyed with the idea of a third-party bid, but later committed to the GOP by signing a loyalty pledge to support the eventual nominee. 

However, Trump, along with Ted CruzRafael (Ted) Edward CruzTrump circuit court nominee in jeopardy amid GOP opposition Trump has officially appointed one in four circuit court judges On The Money: Retirement savings bill blocked in Senate after fight over amendments | Stopgap bill may set up December spending fight | Hardwood industry pleads for relief from Trump trade war MORE and John Kasich, has been backing away from that promise.

Trump met with RNC Chairman Reince Priebus this week. After the meeting, Trump said on Fox's "The O'Reilly Factor": "I think they wanted to really discuss unity, and I like discussing unity, too."

Priebus has said he's not worried about the party coming together after the convention this summer. 

The full interview is set to air on Fox News at 10 a.m. Sunday.