Donald Trump hit back at forces within his party who may try to stop him from formally capturing the Republican presidential nomination, calling their reported plans “illegal,” and after a few rough weeks marked by rising negative ratings he said the general election campaign really hasn’t started.

“First of all, it’s meaningless. Second of all, it’s illegal. Third of all, you can’t do it,” Trump said in Las Vegas on Saturday of the reported plan to unseat him during the Republican National Convention in Cleveland next month.

Trump said that talk of a convention challenge was being manufactured by the media, and that Republican leaders and voters alike were were giving him “tremendous support.”

Tensions have flared regularly between Trump and some establishment figures within the party since he became the presumptive Republican nominee in late May. The Washington Post reported on Friday that Trump critics hope to challenge him in Cleveland by making changes to rules governing the convention. Dozens of Republican delegates were said to be on board.

Rules Committee

Should the efforts gain traction, decisions made by the rules committee before Cleveland could have a big impact on how things play out. On Friday, the RNC named former Representative Enid Mickelsen from Utah to oversee the panel that’s responsible for reviewing and modifying rules for the convention and the party’s operations going forward.

Mickelsen is seen as a potential ally of Mitt Romney, the 2012 Republican presidential nominee who now makes Utah his primary residence and who’s been leading anti-Trump forces within the party. Trump, in turn, has called Romney “a choke artist” for losing in 2012, and Paul Manafort, Trump’s convention manager, last week called the former Massachusetts governor a “coward.”

“We get almost 14 million votes, we win 36, 37 states — others win none. None. Now people who got none are saying, ‘Maybe we can get something at the convention,’ ”a fired-up Trump said in Las Vegas. “It doesn’t work that way, folks.”

Trump said former Florida governor Jeb Bush, one of the more than a dozen Republicans vanquished during the party’s primary elections, may be among those attempting to undermine him. “Jeb is working on the movement, just so you understand,” he said in Las Vegas.

Bush spokeswoman Kristy Campbell responded on Twitter that “Donald Trump’s unending obsession with JebBush is really unhealthy.”

Even Paul Ryan, who has endorsed Trump, clashed with him for what the House speaker said were racist comments on a judge overseeing lawsuits against Trump University, the candidate’s now-defunct real estate training academy. Trump continued Sunday to tell Ryan and other nominal allies to stop such criticism.

“They shouldn’t be talking so much,” Trump said during an interview with CBS’s “Face the Nation.” “Let me run for president.”

Ryan, who will chair the convention, said on NBC’s “Meet the Press” that Trump was the “duly elected nominee” but that delegates could vote their “conscience” in deciding whether to support him. “The last thing I would do is tell anybody to do something that’s contrary to their conscience,” Ryan said.

Negatives Spike

Some Republicans are anxious about the impact on November’s congressional races and other electoral contests of having a standard-bearer who so routinely attracts negative publicity, suggesting that certain potential donors could hold back particularly as they witness a campaign that has largely been slow to ramp up.

Trump said Sunday on “Meet the Press” that his likely rival Hillary Clinton “has a head start,” despite his having become his party’s presumptive nominee weeks before she did for the Democratic Party. “We start pretty much after the convention,” he said in an interview conducted on Saturday.

In Las Vegas Trump said he had raised $12 million to $13 million for the RNC in the past two days alone, and that if Republicans “don’t want to help out as much, I’ll fund my own campaign.”

Polling this week showed Trump’s negative ratings, already high, spiked again after briefly tapering off in May. An ABC News/Washington Post poll released on June 15 found that 70 percent of Americans view Trump unfavorably, up 10 points on the month. Clinton’s unfavorable rating also rose, to 55 percent from 53 percent.