At a summit for young professionals under 30 in Detroit on Monday, President Donald Trump was described as a “moron,” a “whack job” and a “totally vindictive person.”

And that was from a trio of Republicans.

Former Massachusetts Gov. Bill Weld, former U.S. Rep. Joe Walsh of Illinois and former South Carolina congressman and governor Mark Sanford are the three Republicans who have announced that they want to replace Trump as president. Organizers invited Trump to participate in the forum, but he declined. and there was no comparable forum scheduled for Democratic presidential candidates.

And the three spoke to a receptive crowd Monday – millennials attending the Forbes 30 Under 30 Summit, a gathering of thousands of young entrepreneurs and trendsetters.

Their questions centered on climate change, accepting diversity in the country, bringing manufacturing back to the United States and how tariffs are affecting trade policy.

More:NAACP candidate forum: What the contenders had to say

More:University of Michigan to host presidential debate in 2020

But the three candidates were more interested in bashing the guy they want out of office. And they got cheers and widespread applause with each insult.

When asked whether they would vote to remove Trump from office if they were in the U.S. Senate, Weld said, “One thousand times, yes,” and Walsh answered, “Hell yes.” Sanford said he preferred a censure of Trump followed by him being removed from office by voters in November 2020.

“It’s much cleaner to offer a censure and then let the people decide next November,” he said.

Walsh had the most consistent and caustic message about the current commander in chief.

“Donald Trump is a horrible human being. He’s cruel. He’s a bigot. He’s a liar,” he said. “This isn’t about the issues. If Donald Trump wasn’t president, I wouldn’t be here, but he’s a clear and present danger to this country and needs to be gone.”

All three said the Republican Party needs to get back to basics if the party is to survive, as well as acknowledge that climate change is an existential threat that needs to be addressed. They also noted, in contrast to current Republican ideology, that immigrants play an essential role in the nation's economy.

“Freedom is better than government and we old white guys have to make that case to millennials,” said Walsh, the host of a conservative radio show.

Weld, who was the Libertarian candidate for vice president in 2016, said his election success in Massachusetts came from a “rainbow coalition” that included minorities and members of the LGBTQ community.

“I felt it was my duty to make sure everyone felt good about what was going on in Massachusetts,” he said.

And Sanford said all Republicans and voters overall have to do is “look at the numbers” to see that the nation is hurtling toward a disastrous economic fall.

With the national debt rising precipitously and Democrats proposing trillion-dollar programs to provide Medicare for All and pay for the Green New Deal, “that’s what is not being discussed in this election.”

With Trump swamping the competition in fundraising and maintaining high levels of support from the Republican base, the three GOP candidates are a huge long shot.

And with five states — Alaska, South Carolina, Nevada, Arizona and Kansas — already cancelling their Republican presidential primary elections next year, the campaign can hardly even be called a race. While there have been some serious challenges, no incumbent president in modern history has been beaten in a primary race.

“Competition makes all of us better. As a former two-term governor from South Carolina, I think they were afraid something could happen in the primary,” Sanford said. “Someone in the Trump organization is worried. Somebody started looking at the numbers and saw that their support is a mile wide and an inch deep.”

Trump has told reporters, however, that the three candidates’ campaigns are a “publicity stunt.”

“The three people are a joke. They’re a laughing stock,” Trump said in September.

Contact Kathleen Gray: 313-223-4430, kgray99@freepress.com or on Twitter @michpoligal.