Former vice president Joe Biden mocked President Trump’s habit of boasting about his intelligence on Thursday, in one of his most direct critiques of the president ahead of a potential 2020 White House bid.

In a wide-ranging speech in Washington on labor issues and economic policy, Biden told the audience that he had performed well on standardized tests as a student, then quipped: “I’m clearly not as smart as Trump, the smartest man in the world. But I have a relatively high IQ.”

Trump in January praised himself as a “very stable genius” and frequently boasted long before his 2016 presidential run that his IQ “is one of the highest.”

Thursday’s speech marked Biden’s third appearance on the national stage in recent weeks. Late last month, he issued a veiled rebuke of Trump in an emotional eulogy for the late senator John McCain (R-Ariz.) in Phoenix. He also criticized Trump without naming him in a fiery speech for a Democratic House candidate in New Jersey last week.

Economic and labor policy was the focus of Thursday’s “Building a Higher Wage America” summit, and Biden spoke at length on the topic, casting himself as a champion of the middle class and calling for action on issues such as noncompete clauses for low-wage employees.

But politics — and Trump — were clearly on his mind.

As he began his speech, Biden recounted a favorite saying of his father’s: “Don’t compare me to the almighty. Compare me to the alternative.”

“I guess that’s the only reason I’m looking okay these days — the alternative,” Biden said to laughs from the crowd.

He went on to make what appeared to be a dig at Trump’s tweets earlier Thursday falsely accusing Democrats of inflating the number of deaths attributable to Hurricane Maria in Puerto Rico last year.

“By the way, there are no problems in America,” Biden deadpanned. “Everybody’s doing well. Things are fair and decent, and no one died in Puerto Rico.”

Trump also loomed over Biden’s remarks on the minimum wage, which he contended is an issue not just of economics but also about how receptive the public is to populist and nationalist appeals.

“What we’re talking about here today, people being able to earn a decent wage, is the ultimate antidote to all of this foolishness that’s going on with this phony populism and naked nationalism that’s being promulgated right now,” Biden said.

He argued that when people fall on hard economic times, they can be more susceptible to rhetoric from “charlatans who come along, who try to find a reason for those people to blame whatever’s happening to them on the ‘other’ — on the immigrant, on that black man or woman.”

“It’s had an impact here in the United States,” Biden said.

Republicans fired back at Biden’s remarks on the economy.

“Wages are growing faster now than they did during the entire time Joe Biden was vice president. I know he’s eager to run for president (again), but workers are faring far better under this administration,” Republican National Committee spokesman Michael Ahrens said in a statement.

At another point in his speech, Biden criticized noncompete agreements for hourly workers, such as sandwich makers at Jimmy John’s, which abandoned its use of such clauses following a settlement in 2016.

“What the hell is that all about?” Biden asked. “What can that possibly be about except to suppress wages? What other rationale can there possibly be in that?”

He also blasted the practice of employees being forced to sign contracts calling for mandatory arbitration in the event of a dispute, arguing that “people shouldn’t have to sign away their rights to get a job.”

“If a woman is sexually harassed by her boss, shouldn’t she be able to take her case to court, to be heard by an impartial judge and jury?” Biden said. “I’m not saying all employers are bad guys. They’re not. But when they violate basic, fundamental rights, you should be able to step forward.”

The nearly hour-long speech featured several campaign-style flourishes. At one point, Biden looked up to see someone in the room hoisting up a sign.

“You’re holding up a sign. Am I talking too long?” Biden said, before realizing the bearer was encouraging him to make another bid for public office. “Oh, ‘Run Joe!’”

Biden later abandoned the podium and began pacing around the front of the room, addressing the crowd as though he were at a town hall meeting. After a few moments, an organizer handed him a microphone, and Biden apparently decided he had overstayed his welcome.

“Thank you all very much. I’m getting the hell out of here,” he said.