As he warmed up the crowd at his father’s reelection campaign kickoff Tuesday night, Donald Trump Jr. mocked Democratic White House hopeful Joe Biden for saying he wants to cure cancer — an issue Biden has focused on since losing a son to brain cancer in 2015.

President Trump has also pledged to cure cancer, as recently as in his remarks Tuesday night at the same rally in Orlando, where he announced his bid for a second term.

Trump Jr., the president’s eldest son, took several shots at the former vice president during his remarks ahead of his father’s appearance, including one directed at Biden’s announcement last week during a campaign stop in Iowa that he would seek to cure cancer if elected president.

“What was the good one last week?” Trump Jr. told the crowd at the rally. “Remember? Joe Biden comes out, ‘Well, if you elect me president, I’m going to cure cancer.’ Wow, why the hell didn’t you do that over the last 50 years, Joe?”

During his campaign stop in Ottumwa, Iowa, last week, Biden referenced the loss of his son, Beau Biden, the former attorney general of Delaware.

“A lot of you understand what loss is and when loss occurs, you know that people come up to you and tell you ‘I understand’ if you lose a husband, a wife, a son, a daughter, a family member,” he said. “That’s why I’ve worked so hard in my career to make sure that — I promise you if I’m elected president, you’re going to see the single most important thing that changes America, we’re going to cure cancer.”

In his final State of the Union address, delivered after Beau Biden’s death, President Barack Obama asked his vice president to lead a new national effort on eradicating cancer, known as the “Cancer Moonshot.”

After leaving office, Biden also launched the Biden Cancer Initiative, which seeks to build on the work of the government effort.

Sen. Angus King (I-Maine) was among those who criticized Trump Jr.’s remarks at the rally.

“Why would anybody say anything like that?” King said after he was shown a clip of Trump Jr. during an interview Wednesday morning on CNN. “I mean, I’m not usually at a loss for words, but I am on that one. That’s outrageous. You know, for Joe Biden this is a deeply personal issue. . . . To criticize him for it is just ridiculous.”

During his remarks at Tuesday night’s rally, President Trump also endorsed the goal of curing cancer.

“We will push onward with new medical frontiers,” he said. “We will come up with the cures to many, many problems, to many, many diseases — including cancer and others, and we’re getting closer all the time.”

In his speech, Trump also pledged to “eradicate AIDS in America once and for all.”