Trump, who has led the GOP field in poll after poll, has long viewed the threat of a third-party candidacy as priceless leverage – and even used that word when he refused to take such a pledge in the first debate, on Aug. 6.

So his decision to give it up is a sign that he increasingly wants to show his campaign is real and not a stunt. The colorful magnate is also trying to make that point by adding staff in key states, issuing position papers, and pursuing access to primary ballots throughout the country.

Trump is certainly unpredictable, and campaign manager Corey Lewandowski would not confirm the plan. “I don’t think you can ‘expect’ ANYTHING from Mr. Trump,” Lewandowski said in a phone interview.

But the close associate said Trump has decided to give the completed pledge to Republican National Committee Chairman Reince Priebus during a meeting at Trump Tower shortly after 1 p.m. today. Trump is scheduled to hold a news conference on an unspecified topic at 2 p.m.

“The rationale is that they have treated him fairly,” the associate said, echoing the criterion Trump has long given for taking a party pledge. “He’s willing to sign it to avert any problems with is state filings – South Carolina asked for a pledge to support the nominee if you’re on the ballot.

“He’s been treated fairly, like any candidate. … And it takes away a line of attack for debates.”

Priebus will be accompanied by RNC chief strategist Sean Spicer, who has been closely involved in the negotiations.

The meeting has been delicately choreographed. The RNC waited to circulate the pledge until it looked like Trump was on board, and Priebus would not go to Trump’s turf if he thought there was a chance he could be embarrassed.

A top Republican source further explained Trump’s logic: He thinks he could very well be the nominee. And with the pledge in place, the other candidates would have to support him.

The RNC’s draft pledge was first reported Wednesday by POLITICO’s Alex Isenstadt.

The text of the pledge: “I [name] affirm that if I do not win the 2016 Republican nomination for president of the United States I will endorse the 2016 Republican presidential nominee regardless of who it is. I further pledge that I will not seek to run as an independent or write-in candidate nor will I seek or accept the nomination for president of any other party.”

One of the most memorable moments of the first Republican debate came on the first question, when Fox moderator Bret Baier asked: “Is there anyone on stage — and can I see hands? — who is unwilling tonight to pledge your support to the eventual nominee of the Republican Party and pledge to not run an independent campaign against that person?”

Trump drew some boos when he raised his right hand. He explained: “I am discussing it with everybody. But I’m, you know, talking about a lot of leverage. We want to win, and we will win. But I want to win as the Republican. I want to run as the Republican nominee. … I will not make the pledge at this time.”

The next debate is Sept. 16, at the Ronald Reagan Presidential Library in southern California. The associate said Trump knew the third-party issue would again be a distraction, so he decided to close that door.

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