Donald Trump could find his claim to the presidential nomination in jeopardy if he comes into this summer's convention a couple hundred delegates short of 1,237, former Republican National Committee chairman Michael Steele said Friday.
"If Donald Trump goes in there short 200-plus delegates, then it's a whole different ballgame," Steele told CNBC's "Squawk Box." He said if Trump were only 100 delegates short of the magic number it would be hard for party leaders to deny him the nomination.
Trump has 756 delegates, Sen. Ted Cruz has 545 and Ohio Gov, John Kasich 143, according to NBC News.
Trump has been helping his case with GOP establishment officials by acting more presidential recently, Steele said, citing the billionaire real estate mogul's actions Thursday night at a Republican fundraiser in New York City.
"It was interesting because, at the beginning, he did his like 15-minute riff on building buildings here in New York," Steele said. "And then he turned his head down and started to read notes and text. And I was like, wow … because he never does that."
Trump is starting to see himself in the role of president and "doing the disciplined things you need to do," Steele said.
Another aspect of Trump's transformation, according to Steele, has been the candidate's effort to surround himself with experienced political operatives.
Paul Manafort, Trump's new convention manager, brings a higher "level or respectability" to the campaign, Steele said. Manafort has advised Republican presidential campaigns going back to Gerald Ford.
Steele said he has not supported any one candidate, but plans to vote for whomever is chosen as the Republican nominee.
"If Donald Trump is the nominee of my party, I going to go out and I'm going to fight for him to beat Hillary in November," Steele said. "It's not complicated people, either you want Hillary Clinton to be president or you don't."
Clinton is the front-runner for the Democratic presidential nomination.