President Obama on Tuesday declared Donald Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE “unfit” to serve as president, calling on Republican leaders to abandon their support for their own party’s presidential nominee.

“If you are repeatedly having to say in very strong terms that what he has said is unacceptable, why are you still endorsing him?” Obama said during a press conference at the White House with Singapore’s prime minister.

"There has to come a point at which you say, 'enough.' "

Obama lashed out at Trump in the wake of the candidate’s criticism of Muslim parents of a U.S. Army officer who was killed in the Iraq War.

“What does this say about your party that this is your standard bearer?” Obama asked.

“This isn't a situation where you have an episodic gaffe,” he added. “This is daily and weekly where they are distancing themselves from statements he's making.”

It is rare for a president at such a formal setting to rip into a potential successor's ability to serve. Yet Trump's unprecedented campaign, and division within the GOP over it, have given Obama an opening. Rep. Richard Hanna, a retiring congressman from New York, on Tuesday became the first GOP lawmaker to say he would vote for Clinton. Obama said his opponents in 2008 and 2012 — McCain and Mitt Romney — were “wrong on certain policy issues, but I never thought that they couldn't do the job.”

“But that's not the situation here, and that's not just my opinion,” he continued. “That is the opinion of many prominent Republicans.”

Trump released a statement an hour after Obama spoke ripping the president and Clinton for their handling of the economy and foreign policy.

"Obama-Clinton have single-handedly destabilized the Middle East, handed Iraq, Libya and Syria to ISIS, and allowed our personnel to be slaughtered at Benghazi," Trump said.

He said the Iran nuclear deal had put that country on the path to having nuclear weapons, and that Clinton and Obama had let dozens of veterans die while waiting for medical care.

"They have produced the worst recovery since the Great Depression," he said.

Trump also criticized Clinton's use of a private email server as secretary of State, saying it put national security at risk.

Trump has been at the center of a political firestorm over the past week after feuding with Khizr and Ghazala Khan, the parents of the soldier.

One day after Obama spoke at the Democratic convention in Philadelphia, Khizr Khan delivered a blistering rebuke of Trump’s proposal to temporarily ban Muslims from entering the U.S.

Standing beside his wife, Khan questioned whether Trump has ever read the U.S. Constitution while waving a a pocket copy of the founding document. He also said Trump has not sacrificed for his country.

Trump said in an interview with ABC News that he had sacrificed by building his business. And he also suggested the bereaved mother's initial silence was because of her religion.

Trump again responded to Khan’s comments during a Monday night interview on Fox News.

“His son died 12 years ago, and [if] I were president, his son wouldn't have died because I wouldn't have been in the war, if I was president back then,” he told host Sean Hannity.

While no GOP leaders have dropped their endorsement of Trump, Hanna cited Trump's comments on Khan in explaining his decision to vote for Clinton.

“I think Trump is a national embarrassment,” Hanna told The Syracuse Post Standard. "Is he really the guy you want to have the nuclear codes?”

Updated at 1:36 p.m.