PHILADELPHIA — For a former vice president now working as a college professor, Joe Biden sure sounded like a presidential candidate Tuesday as he paced the stage at the University of Pennsylvania before a ticketed crowd of hundreds of students.

He said he was more optimistic about the country than ever. He laid out a vision for reversing President Trump’s foreign policy. He demanded new worker protections to build up the middle class. And at times, amid a stream of folksy aphorisms and familiar anecdotes, he allowed his voice to rise to something like a rallying cry.

“We can do anything! Not a joke! Not a joke!” he boomed at one point. “It’s the nature and character of the people who built this country.”

But Biden would not address the one thing on everyone’s mind: Would he throw his hat in the ring to challenge Trump at the ballot box next year?

Rather, he continued an act he has practiced for more than a year, teasing his own credentials and road-testing the messages that would form his campaign before a friendly audience in an unobtrusive setting.

Biden, 76, has let repeated self-imposed deadlines pass for deciding on a third presidential run.

Some advisers have admitted the delays have come with a cost, as potential campaign staffers sign up with other campaigns and other candidates get a head start in meeting voters in early primary states. Others have said Biden has the luxury of waiting, given his high favorability rating within the Democratic Party and a network of donor relationships he established during Barack Obama’s two presidential campaigns.

Either way, he seems to be taking his current speaking tour seriously. He walked onstage Tuesday with a set of notecards he could refer to as he made the case for a different approach to European allies, Central American corruption and the automation of the retail sector. He spun yarns about his dealings with Russian President Vladimir Putin, Chinese President Xi Jingping and his old boss, Obama.

He also made clear that he would pull few punches against the current occupant of the Oval Office. He called the Trump administration’s lack of support for the European Union “the dumbest thing in the world,” and he blistered Trump for saying there were good people on both sides of a clashes over a 2017 white nationalist rally in Charlottesville.

“Not a joke. Think about it. No president since the Civil War has uttered words remotely like that,” he said. “So it is time to restore America’s soul.”

Trump, who also condemned racism after the Charlottesville protests, has repeatedly attacked Biden, most recently in an interview this month with the New York Times. “I hope it’s Biden,” Trump said of the Democratic nominee. “When Biden says something dumb, it’s because he’s dumb.”

If he decides to run, Biden will enter the most crowded Democratic field in modern memory. With the number of presidential hopefuls growing, the Democratic National Committee announced Thursday that no more than 20 candidates would be allowed to participate in the first party debates this summer.

Since the start of the year, six U.S. senators, two current or former mayors and one member of Congress have joined former congressman John Delaney of Maryland in the race for the 2020 nomination. At least 14 other Democrats, including four current or former governors, say they will announce their decisions in coming months.

Tuesday’s setting was a performance hall at the University of Pennsylvania, where Biden is a professor of “presidential practice” at the PennBiden Center for Diplomacy and Global Engagement. University President Amy Gutmann, his onstage interrogator and employer, delivered a series of softball questions, with some trivia mixed in.

She asked him about his friendship with Lady Gaga and about his dog Major, whom Biden adopted late last year as a companion to his other pooch, Champ.

“Major is doing well, taking care of Champ,” Biden said.

The appearance comes in the middle of a transcontinental speaking tour for Biden. On Saturday he attacked Trump’s foreign and immigration policies at the Munich Security Conference in Germany, calling the administration’s refugee and child separation policies an “embarrassment” and telling European leaders that most of the American people do not support America’s withdrawal from international alliances.

“I promise you, as my mother would say, ‘This too shall pass,’ ” he said. Trump has described those policies as critical for national security.

Biden addressed black leaders in January to explain his support for tough-on-crime policies in the 1990s, which led to what most experts agree have been disproportionate sentences for nonwhite convicts. “I haven’t always been right,” he said at an address to the Rev. Al Sharpton’s National Action Network on Martin Luther King Day. “I know we haven’t always gotten things right, but I’ve always tried.”

He will be interviewed onstage Feb. 26 about his views on American history at a celebration for the recently named Joe Biden School of Public Policy and Administration at the University of Delaware, followed by a Feb. 28 discussion of foreign policy at the inaugural Chuck Hagel Forum in Global Leadership at the University of Nebraska at Omaha.

As Tuesday’s event ended and Biden posed for pictures onstage, a member of the departing audience shouted for him to run for president.

Biden did not respond.