ROME — Donald Trump sought to motivate his supporters Tuesday by airing grievances against the Republican National Committee, the presidential primary process and rival Ted Cruz, urging backers not to let others use “dirty tricks” to steal the GOP nomination from him.

Trump, at a rally inside a former air base hangar here, hit many of his usual talking points — foreign trade, Obamacare, the Islamic State group, his claim that the U.S. “doesn’t win any more” — mixed with declarations of strength: “My numbers now are better than Ronald Reagan against Jimmy Carter” and “I was the best thing to happen to Bernie Sanders.”

But there was an increased emphasis — with New York’s crucial primary just a week away — on his contention that voters had to help him prevent others from denying him the nomination.

“We’ve got to show our Republican Party that we’ve been disenfranchised. They can’t get away with this stuff any longer,” Trump told the crowd of roughly 5,000.

Trump is the lone candidate with a realistic chance of securing the 1,237 delegates necessary to clinch the nomination before the party’s convention in July, but he might need to sweep most or all of New York’s 95 delegates to get there. He underscored the importance of winning his home state with a joke, saying he might have to “move south” if New York didn’t treat him right. He even said if he didn’t ultimately win, he would consider his efforts a “massive waste” of time and money.

His tactical grievances were in reference to maneuvering by Sen. Ted Cruz (R-Texas) to lock up all 34 Colorado delegates at a caucus last week. Trump said the RNC “should be ashamed of itself. . . . They took the vote away from the people in Colorado.”

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Analysts have countered that the Trump campaign’s lack of knowledge about the Colorado caucus rules is what sunk him, and that his campaign did insufficient leg work to court the state’s delegates.

Trump, though, was having none of it.

“They say, ‘Oh, that’s the way the game is played,’ ” Trump said in an attempt to fire up the audience. “The system is set up for crooked politicians.”

He added, to a chorus of boos: “Don’t forget lyin’ Ted Cruz.”

Ohio Gov. John Kasich, who is running third, has said repeatedly no one will arrive at the convention with a majority — a notion Cruz also says is increasingly likely.

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With some Republicans working to block the real estate mogul and create a contested convention, Trump’s campaign has acknowledged that a huge victory in New York might be necessary for him to reach the 1,237 delegates he needs to snag the nomination.

To sweep New York, he has to get more than 50 percent of the vote in each of the state’s 27 congressional districts — a feat his backers predict he will achieve.

“Get out and vote on Tuesday,” Trump said in closing. “I will not let you down.”