President Obama and Vice President Joseph R. Biden went on the attack Tuesday against Donald Trump, arguing that the Republican nominee proved in the first presidential debate he’s a soulless businessman who doesn’t understand the middle class.

While barely touching on the attributes of Democratic nominee Hillary Clinton, Mr. Obama in a radio interview and Mr. Biden in a campaign speech said Mr. Trump’s candidacy must be defeated, after a stretch in which the Republican has pulled even or slightly ahead of Mrs. Clinton in several battleground states.

They also appealed to young people to register to vote, reflecting the deep concern among Democrats that millennials are abandoning Mrs. Clinton in droves. Voters in the 18-to-34 age range were a key part of Mr. Obama’s winning coalitions in 2008 and 2012.

“I know a lot of students on campus are frustrated,” Mr. Biden said at a rally at Drexel University in Philadelphia. “I know they’re not overjoyed about the choices. I know they think that Hillary didn’t do A, B, C or D. But my Lord, my Lord, what are we going to do?”

Mr. Obama, who watched the Monday night debate on TV at the White House, said Mr. Trump “doesn’t have the preparation, the temperament, or the core values of inclusion and making everybody have opportunities that would take our country forward.”

The president said he’s particularly worried about Mr. Trump being in charge of the U.S. nuclear arsenal.

“I always worry about nuclear proliferation, and that’d be a game-changer and that’s why I spent a lot of time working to make sure that, for example, Iran doesn’t get nuclear weapons,” Mr. Obama told radio host Ryan Seacrest. “That’s why I get worried when somebody like Donald Trump start saying, ‘Well, I don’t necessarily know whether Japan or Korea should be protected by us. Maybe they should get their own nuclear weapon.’ That shows somebody who doesn’t pay attention to these issues, and you don’t necessarily want close to the nuclear button.”

Mr. Biden was especially harsh in his criticism of Mr. Trump, telling students that the Republican lacks the “moral center” to lead the nation. He said Mr. Trump showed his callousness during the debate by boasting about not paying taxes and profiting from the housing crisis.

“He acknowledged that he didn’t pay taxes because he said he’s ‘smart,’” Mr. Biden said, seething. “Tell that to the janitor here who’s paying taxes. Tell that to your mothers and fathers who are breaking their necks to send you here and are paying their taxes. It angers me.”

The vice president criticized Mr. Trump for bragging about “profiting off of the misery” of people who lost their homes or equity during the recession. Mr. Biden said it was the middle class “who built this damn country.”

“What does it say about this man?” Mr. Biden asked. “He wants to be president of the United States of America. He does not have the basic, fundamental sensibilities and values that almost every American politician, left right and center, I know, have.”

Pennsylvania is a crucial battleground state, and recent polls show the candidates essentially tied, with Mrs. Clinton having lost a sizable lead. The campaigns are battling especially hard for voters in the Philadelphia suburbs, and for young voters who Mrs. Clinton has yet to win over.

“We need you badly,” Mr. Biden told students.

In his appeal to young voters, the vice president suggested a way for the government to pay for Mrs. Clinton’s proposal for free college tuition.

“The way we do it is to get guys like Donald Trump to pay their taxes,” he said.

Mr. Biden said Mr. Trump, who claims the political system is “rigged,” is himself benefiting from a rigged banking system. He questioned why the Republican nominee has been able to secure business loans while his companies have declared bankruptcy five times.

“He brags about gaming the system and bankruptcy, leaving hard-working people holding the bag. How many people has he stiffed?” Mr. Biden said. “That’s the rigged system. He is part of the rigged system.”

At the White House, Mr. Obama’s spokesman poked fun at Mr. Trump’s assertion that Federal Reserve Chairwoman Janet Yellen is playing politics in her management of the central bank by keeping interest rates low during Mr. Obama’s tenure.

“The charge of course is preposterous, and it is baseless,” said White House press secretary Josh Earnest. “There has been no evidence to marshal to support it.”

In the debate, Mr. Trump said the Fed under Ms. Yellen’s leadership “is being more political than Hillary Clinton.”

“We have a Fed that’s doing political thing — this Janet Yellen of the Fed — by keeping interest rates at this level,” Mr. Trump said. “The day Obama goes off … playing golf for the rest of his life, when they raise interest rates, you are going to see some bad things happen.”

Mr. Earnest said he found the Republican nominee’s claim laughable.

“I chuckled when he said that she was more political than Hillary Clinton. I’m not even sure what that means,” he said.

The White House insisted that the Fed is not susceptible to partisan politics.

Sign up for Daily Newsletters Manage Newsletters

Copyright © 2020 The Washington Times, LLC. Click here for reprint permission.