In a fiery speech from Scranton, Pa., the city where he was born, Biden blasted the Republican nominee as “unqualified” to serve as commander in chief, arguing he lacks the necessary foreign policy knowledge and the willingness to learn.

Biden accused Trump of finding common cause with some of history’s most reviled leaders in an address that drew several rousing ovations from the hometown crowd.

The vice president keyed in on Trump’s recent comments, which he later said were sarcastic, that he hoped Russia had copies of Clinton’s private emails.

“This guy’s shame has no limits,” Biden said. “He’s even showered praise on Saddam Hussein, one of the vilest dictators of the 20th century … He would’ve loved [Joseph] Stalin.”

Biden said Trump’s praise of strongmen for cracking down on their political foes and support for harsh interrogation tactics of terror suspects “says a lot about his approach that explains why he so often embraces tactics of terrorist enemies themselves.”

He also said he would have urged his late son, Beau, not to serve in the military if Trump were president.

“If my son were still in Iraq, and I say to all those who are there, the threat to their life has gone up a couple of clicks,” he said.

The vice president’s eyebrow-raising comments were meant to undercut Trump’s speech later Monday in Youngstown, Ohio, in which he planned to lay out his plan to defeat the Islamic State in Iraq and Syria (ISIS).

“The rise of ISIS is the direct result of policy decisions made by President Obama and Secretary of State Clinton,” he told supporters in the northeast Ohio city. He shifted away from his much-criticized contention that Obama actually founded ISIS. But he argued that the situations in countries such as Syria, Libya and Egypt and Iraq all worsened under Obama’s leadership. “The decisions made by the Obama/Clinton group have been absolutely disastrous," he said. He’s hoping that tough tone on terrorism, combined with his populist economic rhetoric, will help win over white, working-class voters in battleground states like Ohio and Pennsylvania. Trump attacked Clinton’s effort to weed out Islamic terrorist groups at home and abroad during her tenure as President Obama’s secretary of State.

That contest will play out in places like Scranton, a former mining town of more than 75,000 that is overwhelmingly white.

The Clinton campaign is relying on Biden, who has long been known for his everyman appeal, to help undercut Trump’s support among those voters.

Without wining in Ohio and Pennsylvania, Trump could have difficulty winning enough electoral votes to take the White House in November.

Biden once considered running against Clinton in the Democratic primary. But any signs of lingering tensions were put aside on Monday.

The vice president held Clinton in a long embrace on the tarmac in Scranton. And he held her hand up as the crowd cheered at the conclusion of his speech.

“I hope you know how much not just Scranton but America loves you and your family,” she told Biden on stage.

When her campaign first announced the Scranton rally with Biden in early July, which was postponed by the Dallas police shooting, she looked to be in trouble with voters in the Rust Belt.

But recent polls show her building her advantage in the Keystone State as Trump’s campaign has suffered from a series of public missteps. A Quinnipiac University poll released last week found Clinton leading Trump in the state by 10 points.

Biden offered a personal testimonial for Clinton during a folksy speech that played up his and Clinton’s family connections to Scranton.

Clinton’s father hails from Scranton, and both she and Biden recalled childhood memories to show they had embraced the town’s working-class values.

He cast Clinton as the best leader for the American middle class. He also said that her election would serve as a powerful example for women and girls.

“She gets it,” he said. “What it will mean to them what it means when it’s President Hillary Rodham Clinton. It will change their lives.”

He discussed his decades-long relationship with Clinton and recalled how they had weekly breakfasts together to discuss pressing issues facing the country.

“There’s only one person in this election who will possibly help you, and that is Hillary Clinton,” he said. “She has always been there, that’s her life story.”

Biden also laced into Trump, torching the billionaire as not understanding middle class problems.

“Let’s state the obvious, that is not Donald Trump’s life story,” Biden said. “What bothers me most about Donald Trump, is that his cynicism is unbounded.”

Channeling a memorable line from his speech at the Democratic convention, Biden said Trump’s claim to stand up for the middle class is “such a bunch of malarkey.”

This story was updated at 3:57 p.m.