Republican presidential candidates are feeling increased pressure to sign a pledge saying that if they don’t win the GOP nomination they will support whoever the nominee is.

The Republican National Committee has made signing the pledge one of the requirements to participate in the first debate on Aug. 23. And now the Florida Republican Party is requiring candidates make such a commitment to appear on the ballot for the state’s March 19 primary.

Christian Ziegler, the Florida GOP chairman, told the USA Today Network in Florida that the pledge requirement was “requested and passed by our members to ensure maximum unity.”

“Contested primaries are part of the process, but we must always remember that the Democrats are the true threat to the America we love and we must be unified to defeat every single one of them,” he said.

The candidates must pledge to endorse the nominee and not run as an independent or third-party candidate.  The winner of the all-or-nothing primary will gain 125 delegates toward the nomination.

Not all candidates are rushing to make that promise.

North Dakota Gov. Doug Burgum, conservative radio host Larry Elder, former Ambassador to the United Nations Nikki Haley, U.S. Sen. Tim Scott of South Carolina and Miami Mayor Francis Suarez have all said they will support the eventual nominee.

Former New Jersey Gov. Chris Christie has said he would sign the pledge, but has suggested, if former President Donald Trump is the nominee, he won’t honor it, calling it a “useless idea.”

“I will do what I need to do to be up on that stage,” Christie told CNN last month. 

“I’m going to take the pledge just as seriously as Donald Trump took it in 2016,” he added.

In 2016, Trump vowed to support the eventual nominee but later changed his mind, saying it would depend on the candidate. This time around, he has so far made similar comments about a pledge. 

Trump also has suggested he might skip at least one of the early GOP debates, making the RNC’s requirement potentially moot. But the new Florida mandate significantly changes the calculation for all candidates who have expressed reservations about signing the agreement.

Former U.S. Rep. Will Hurd of Texas is the only candidate to say he will refuse to sign the pledge.

Five candidates — Trump, former Florida Gov. Ron DeSantis, former Vice President Mike Pence, former Arkansas Gov. Asa Hutchinson and entrepreneur Vivek Ramaswamy — have sent mixed messages.

Most of those hesitant to sign the agreement have pointed to Trump, who is facing two indictments, one for allegedly falsifying business records in New York and the other over his handling of classified documents after leaving the White House. 

Hurd told CNN on Thursday that even if it costs him a spot on the debate stage or the Florida ballot, he cannot say he would support Trump. 

“I can't lie,” Hurd said, citing concerns about Trump’s electability in a general election and his handling of national secrets. 

DeSantis, one of Trump’s favorite targets in attacks in recent months, sidestepped questions last month about whether he’d endorse Trump, citing insults the former president made about DeSantis’ response to the COVID-19 pandemic.

DeSantis’ comments, however, came before Florida announced its pledge requirement.

The Florida governor also said that the primaries are “an important process and, you know, you respect the process and you respect the people’s decisions how this goes.” 

Hutchinson has said he would not vote for Trump if he’s convicted of a felony and asked the RNC to clarify that the pledge would not apply in such an instance. The RNC, however, reportedly told a Hutchinson staffer in a “contentious” call that it’s “not dealing with hypotheticals.” 

Ramaswamy initially said he would support whoever voters elect as the nominee, but he later changed his position, saying, “If the other candidates in this race make that pledge, I will stand by and be willing to.”