The blunder came after mocking President Joe Biden who stumbled upon a word in a video clip. The former president was listing candidates he supported when he made the mistake. “You know, we supported Dr. Oz, we supported JP, right? JD Mandel, and he’s doing great. Everything is going well,” Trump told the crowd at I-80 Speedway in Greenwood. Vance is running for the Republican Senate in Ohio against Josh Mandel and Mike Gibbons in Tuesday’s primary. Former President Donald Trump has said he approved of “JD Mandel” in a blunder at a Save America rally in Greenwood, Nebraska, on Sunday. Above, he gives two thumbs up to the crowd at the Republican National Convention on July 21, 2016, at the Quicken Loans Arena in Cleveland, Ohio. CHIP SOMODEVILLA / GETTY IMAGES The mistake came after Trump called Biden to take a cognitive test and boasted of his own perfect results. “Once and for all, Joe Biden should put an end to the question by taking a cognitive test; making the results public so everyone can see them,” Trump said. Trump boasted about the results of his own cognitive test and said that former White House doctor Dr. Ronnie Jackson once called him a “perfect sample.” Trump said he took the test to “put an end to this fuss” of people calling him by name, and that Jackson told him the test was “tough.” “I accepted it,” Trump said. “Every question is correct. One person said, ‘I have never seen an ace before.’ Earlier in the day, Trump described Biden as “someone who shames our country.” “Meanwhile, we have a president who has no idea what’s going on, who shakes hands with Putin, while Putin talks about nuclear weapons all the time,” Trump said. Trump also showed an excerpt from the president’s speech last week, in which Biden coined the word “kleptocracy.” Biden speaks openly about his stuttering, a struggle from his childhood. Trump was in Nebraska backing Gov. Charles Herbster, who has made headlines in recent weeks over allegations that he stroked eight women, including Republican Sen. Julie Slama in 2019. The Nebraska primary election is on May 10. Earlier in the rally, Herbster’s speech focused on immigration, China, and critical theory of race. “The illegals are coming after us, the drug people are chasing us,” Herbster said. “It’s happening in Nebraska. We have to stop it. I will meet them at the border.” Herbster said he supported “legal immigration”, but offered a “Nebraska checklist” for those interested in living there, saying they should “honor God, our flag and learn to speak English”. In terms of education, he pledged to end racial critique and remove sex education from schools. “There will be no critical race theory in any school system, including the university,” Herbster said. Herbster called China “the worst enemy outside the country.” “China, listen to me very carefully, China wants to take us down. Do you understand that? Every day … it penetrates the United States of America. As your governor, China will not buy a single acre of land in the state of Nebraska. “ Trump’s rally has been postponed since Friday due to severe weather. He is expected to hold another rally Friday in Greensburg, Pennsylvania, in support of Dr. Mehmet Oz, who is seeking the candidacy of outgoing US Senator Pat Tumey in the May 17 primary. Newsweek contacted Trump for comment.