Richard Shiro, File, Associated Press
FILE - In this Aug. 27, 2015 file photo, Republican presidential candidate Donald Trump greets supporters after speaking at a rally at the TD Convention Center in Greenville, S.C. NBC announced Tuesday, Sept. 1, that Trump will sit down with host Jimmy Fallon to discuss his campaign and other issues on "The Tonight Show Starring Jimmy Fallon," on Sept. 11.

WASHINGTON — The Republican National Committee has challenged every GOP presidential candidate to sign a pledge not to undertake a third-party bid in 2016 under any circumstances.

The challenge, confirmed by multiple campaigns on Wednesday, is aimed squarely at Donald Trump.

The billionaire businessman last month repeatedly threatened to launch a third-party bid should he fail to claim the Republican presidential nomination. Such a bid would make it all but impossible for the Republican Party to win the White House in 2016.

Republican National Committee Chairman Reince Priebus is set to meet privately with Trump in New York City on Thursday, where Trump is also scheduled to speak to reporters. The private meeting is confirmed by an RNC official who wasn't authorized to discuss Thursday's plan publicly.