Donald Trump has the temperament of a right-wing radio talk show host — bombastic, bullying, crude and insulting. It’s a style that has long been influential in the Republican Party. Now it’s taking over.

Talk radio is an ideal medium for conservatives. A few liberals have tried it, but they’re not very good. Liberal talk radio is National Public Radio and its flagship show, “All Things Considered.” Trump does not consider all things. He considers what he damn well wants to consider.

What Trump has is attitude. After all, Trump’s signature line from his reality TV show was “You’re fired!”

A former senior adviser to Sen. John McCain’s 2008 Republican presidential campaign explained the support for Trump this way: “We have reached a moment where conservatism isn’t defined by issues any more.” In fact, Trump is out of line with conservative orthodoxy on many key issues.

Right-wing radio talk show hosts have been Republican Party boosters for decades. It was made very clear in 1994. Rush Limbaugh, the voice of angry white men, took credit for the first Republican takeover of the House of Representatives in 40 years.

Trump, now the front-runner for the 2016 Republican presidential nomination, is a kindred spirit. Michael Savage, a leading voice on right-wing radio, said Trump’s candidacy “made me more proud of myself.”

Consider these statements:

“I think we should simply invade Cuba and overthrow the communist regime. Then maybe America could have Miami back.”

“The people who own the country, pay the bills, pay the taxes, they get indentured to the new people who are not even supposed to be here. Isn’t that a lot like slavery?”

“Muslims can come in (to the United States) but Christians can’t, and the Muslims aren’t in danger but the Christians are.”

The first two were made on talk radio. The third was said by Trump.

Crude insults are rampant on talk radio. In 2012, Limbaugh, for example, focused a series of shows on a Georgetown University woman law student who testified before House Democrats in support of mandating insurance coverage for contraceptives. “What does that make her?” Limbaugh asked. “It makes her a slut, right?”

This year, Trump denounced McCain, who was a prisoner of war for 5½ years. “He was a war hero because he was captured,” Trump said. “I like people who weren’t captured.”

When former Florida Gov. Jeb Bush criticized him in Spanish (Bush’s wife is from Mexico), Trump said, “He should really set the example by speaking English while in the United States.”

The Republican Party establishment is horrified. “He personalizes everything,” Bush complained. “If you’re not in total agreement with him — you’re an ‘idiot,’ or ‘stupid’ or you don’t have ‘energy.’ ” Energy? Radio talk-show hosts are manic.

Bush promotes an alternative approach, most conspicuously on immigration. “You win campaigning with your arms wide open,” Bush said in Reno last month. “You win with joy in your heart.”

A veteran Florida lobbyist told The New York Times, “Donald Trump epitomizes everything that Jeb has spent his political career trying to prevent the Republican Party from becoming.” Meaning, the party of older conservative white men.

Talk radio isn’t very nice. Neither is Trump. Trump noticed that in a recent poll of Republican primary voters, he led his rivals on every issue and quality but one. “The only thing I did badly on was, ‘Is he a nice person?’ ” Trump observed with dismay. “I was last in terms of niceness.” Were his feelings hurt? Apparently not. “We don’t need ‘the nice,’ ” Trump said. “We need competent.”

But Republicans do need nice. Over the years, the conservative movement has created a damaging stereotype of Republicans. The stereotype is mean and nasty: former House Speaker Newt Gingrich, Limbaugh, former Vice President Dick Cheney. A member of Congress shouting “You lie!” at President Barack Obama during an address on the House floor. The audience at a 2012 Republican primary debate booed a gay American soldier.

President Ronald Reagan defied the stereotype. He showed generosity of spirit. To conservatives, Reagan’s biggest mistake was signing an amnesty bill in 1986 that granted legal status to millions of undocumented immigrants. Reagan sometimes did say harsh, divisive things. But in the end, voters knew Reagan wouldn’t start a war or throw old people out in the snow.

With Trump, they can’t be sure.

Nice conservatives get elected because they defy the stereotype. In 2000, George W. Bush promised to be “a uniter not a divider.” Voters believed he was like his father — “kinder and gentler.” That’s the kind of campaign Jeb Bush is running.

But look at what’s happening. Trump is beating Bush 3-to-1 among Republican primary voters.

Last week, Trump signed a pledge not to run as an independent next year. And to support whichever candidate wins the Republican nomination. The Republican establishment is claiming victory.

But the other contenders will have to sign the same pledge. Which means that if Trump wins the Republican Party’s nomination, they agree to support him.

Some years ago, I spoke to a convention of radio talk show hosts. The atmosphere was that of a men’s locker room, full of tough guy talk. They all saw Limbaugh as a god.

Now they worship at the feet of Trump.

Bill Schneider is professor of public and international affairs at George Mason University.