RNC chair: Donald Trump "will be the presumptive nominee"

Reince Priebus expects that Donald Trump will soon have the delegates needed to become the GOP nominee, the Republican National Committee (RNC) chairman said in an interview with "CBS This Morning" after the Indiana primary.

"My belief is that he will be the presumptive nominee," Priebus said early Wednesday morning. "You're not the presumptive nominee until you hit 1,237 [delegates] - that being the case, I'm just stating the obvious."

Shortly after Ted Cruz announced the suspension of his campaign after a blistering loss in Indiana, Priebus took to social media with a tweet saying that the party must now back Trump and "focus on defeating" Clinton:

The RNC chair repeated that call early Wednesday, saying "it's time to unite" and blasting Democrats for their own lengthy primary process.

"I said a couple months ago I thought that the Republican party would end up with more clarity sooner than the Democrat party and look at where they're at," Priebus said. "Once again, Bernie Sanders wins again in Indiana when actually Hillary Clinton was expected to win. You know at some point Hillary Clinton is going have to start winning something somewhere."

He slammed Clinton -- who has won the backing of 1,645 pledged delegates according to the most recent CBS News estimates -- as "nowhere near putting boots on the ground" for the general election. The former secretary of state needs just 17 percent of all remaining delegates to clinch her party's nomination.

Priebus further defended the Republican party's "pretty historic" primary contest, citing voter registration rates and fundraising metrics.

"Our fundraising in the first quarter of the RNC was an all-time record," he said. "We've raised more money what we did in 2012. What I'm telling you is the fundamentals are actually the opposite of the narrative."

He admitted, however, that it was a "hard" year-long slog through the campaign season.

"I would be lying to you all if I said, 'okay this is going to be easy, we're just going to pivot,'" Priebus said. But, he added, "we need time to unify and we will unify -- but this is what today starts. It's this unification process."

When asked about the low rates of support among white voters for Trump in key battleground states, Priebus acknowledged that "there's work to do," especially among minority voters. But he pledged that the party -- and, by extension, the party's expected nominee -- was committed to doing that work.

"It's not gonna be overnight and instantaneous but we're gonna work at it," he told CBS. "We've been working at it for four years. I think Donald Trump is ready to roll up his sleeves and get to work." When asked about whether Ohio Gov. John Kasich should stay in the race, Priebus said, "It's up to him."

Prior to his victory speech at Trump Tower Tuesday night, the billionaire spoke to Priebus over the phone. Despite their previously tense relationship, where Trump has accused the RNC of attempting to steal the nomination away from him, the New York business mogul commended Priebus' work Tuesday.

"He's doing a tremendous job," Trump, on stage, said of the RNC chair. "It's not an easy job when he had 17 egos. And now I guess he's down to one. I don't know, is there a second? I mean, is there a second? I don't know. I'm going to have to ask you folks to explain the status of that."