The establishment has been trying to stop Trump since he started.
Trump warns there could be riots if the GOP steals the nomination from him.
The outspoken New York businessman scored big wins in primaries in Florida, Illinois, Missouri and North Carolina on Tuesday, knocking out rival Marco Rubio and bringing him closer to the 1,237 convention delegates he needs to win the nomination.
But Trump lost the crucial state of Ohio, and left the door open for those in the party trying to stop him from becoming the Republican nominee for the Nov. 8 election.
Trump might fall short of the majority required, enabling the party’s establishment to put forward another name at the July convention in Cleveland to formally pick its candidate.
In an interview with CNN on Wednesday, Trump said the party could not deny him the nomination should he fail to win enough delegates.
“I don’t think you can say that we don’t get it automatically. I think you’d have riots. I think you’d have riots. I’m representing many, many millions of people.”
While the Republicans were mired deeper in turmoil, Hillary Clinton won victories in five states on Tuesday that put her in good shape to defeat U.S. Senator Bernie Sanders of Vermont and win the Democratic Party’s nomination.
Republican Party leaders are appalled at Trump’s incendiary rhetoric and reject policies such as his vow to deport 11 million illegal immigrants, temporarily ban Muslims from the United States and build a wall along Mexican border.
The party tried to play down his riot comments.
“First of all, I assume he is speaking figuratively. If we go into a convention, whoever gets 1,237 delegates becomes the nominee. It’s plain and simple,” Republican National Committee spokesman Sean Spicer told CNN.
Recent outbreaks of violence during protests at Trump rallies have prompted President Barack Obama, a Democrat, and mainstream Republican figures to speak out against the billionaire.
In comments likely to raise more concern in the Republican establishment about Trump’s lack of experience and temperament, the former reality TV show host said he was for the most part his own foreign affairs adviser.
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“I’m speaking with myself, number one, because I have a very good brain,”he told MSNBC’s “Morning Joe” show. “I know what I’m doing. …My primary consultant is myself.”
Voters have roundly rejected the moderate wing of the Republican Party — often represented by the likes of previous presidential nominees Mitt Romney and John McCain — in the 2016 campaign, although it is still a powerful force in Congress.
Trump’s closest national challenger is first-term U.S. Senator Ted Cruz, a Texan and favorite of the Tea Party who prides himself in being a grassroots conservative often at odds with Republican leaders.
“I think that would be an absolute disaster. I think the people would quite rightly revolt,” Cruz told CNN.
If no candidate wins enough delegates, the party needs to pick its nominee at the convention by following a complex process of sequential votes that would likely lead to horse trading.
The Republican establishment’s bid to stop Trump may have come too late as the field of candidates has dwindled to only three, with Trump, 69, in command ahead of Cruz, 45, and Ohio Governor John Kasich, 63, who won his state’s Republican primary on Tuesday.
Kasich, a former investment banker, is the last moderate Republican presidential candidate standing but he has won only his home state’s primary so far.
Trump now needs to win about 55 percent of the roughly 1,100 delegates still up for grabs in state-by-state nominating contests to guarantee the nomination. It is not an insurmountable challenge.
Republican strategist Ron Bonjean said it might be tough for the party to block Trump.
“A contested convention would be justified if Trump only had around 35 or 40 percent of the delegates locked up. However, if he is very close to getting the majority of delegates, it would be politically difficult for the establishment to try stop him by backroom wheeling and dealing without risking a serious backlash from voters,” said Bonjean. The strategist is not affiliated with any of the candidates.