Joe Biden hit the campaign trail for the first time as a 2020 Democratic presidential candidate Monday, preaching a populist message of restoring the country’s middle class as well as throwing some jabs at President Trump.

"The middle class is hurting, it’s hurting now,” the former vice president told supporters at a Teamsters union hall in Pittsburgh.

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“The stock market is roaring. But you don’t feel it. There was a $2 trillion tax cut last year. Did you feel it? Did you get anything from it?” Biden asked as the audience chanted ‘No.”

Speaking in front of a standing room only crowd, with an overflow watching on a big video screen outside, Biden touted his longstanding support of and ties to organized labor, eliciting loud cheers by declaring “I make no apologies, I am a union man.”

He vowed to "fight like the devil" for organized labor and called union busting efforts "morally wrong.”

Biden kicking off of his initial six-state, three-week long campaign swing in Pennsylvania came as no surprise. The Keystone State, long a crucial battleground in presidential elections, was one of three key Rust Belt states -- along with Michigan and Wisconsin -- that Trump flipped into the Republican column in 2016 to help him capture the White House.

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While Biden has long lived in Delaware and represented that state for nearly four decades in the Senate, he was born and spent his early years in Scranton, Pa., and the state has always remained special to him. The stops in Pennsylvania are meant to signal that Biden is determined to recapture working-class voters swayed by Trump’s populist message in 2016.

“I believe that Pittsburgh and my native town of Scranton ... represent the cities and towns that make up hard working, middle-class Americans who are the backbone of this nation,” Biden explained.

“I also came here because quite frankly folks, if I’m going to be able to beat Donald Trump in 2020, it’s going to happen here, in western Pennsylvania, with your help,” Biden highlighted. “Places where a little lately we’ve had a little bit of a struggle. But the truth of the matter is I think we’re coming back.”

But hours before Biden arrived in western Pennsylvania, the Republican National Committee spotlighted figures showing the jobless rate in Pittsburgh dropped from 5.2 percent to 3.9 percent since Trump took over in the White House. And the RNC added that 5,000 manufacturing jobs have been added in the city during the Trump administration.

“In 8 years as VP, Biden did not deliver for Pennsylvanians, while in just over two years into the Trump presidency Pennsylvania’s economy is now booming,” the RNC argued. “Biden is going to have a tough time explaining to Pennsylvanians why they would want to go back to the Biden-Obama economy.”

And early Monday, the president took to Twitter to question why Biden chose Pittsburgh as the site of his first campaign speech.

"Sleepy Joe Biden is having his first rally in the Great State of Pennsylvania. He obviously doesn’t know that Pennsylvania is having one of the best economic years in its history," Trump wrote.

But Biden took aim at Trump’s signature domestic achievement, saying: "It's time to start rewarding work over wealth. The first step is reversing President Trump's tax cut for the very wealthy and corporations.”

And he emphasized that “it’s well past time that minimum wage nationally should be a minimum $15.”

Biden told the audience, estimated at 600 by the fire marshal, that "our political system is broken. We're tearing America apart instead of lifting it up. And the major moral obligation of our time is to restore, rebuild, and respect the backbone of America, the middle class.”

And speaking to a party that showcases the most diverse roster of presidential candidates in history, the former vice president added that “as we rebuild it, we need this rebuilding to be all-inclusive, opening the doors of opportunities for all Americans, no matter their race, their gender, who they love, no matter who or where they’re from, no matter whether or not they have a disability.”

In his 26-minute speech, Biden also called for “access to affordable education so everyone can get the skills they need” as he pointed out that 65 out of 100 jobs today require post-high school education.

And he called the Affordable Care Act, better known as Obamacare, "a huge step forward," vowing if elected to “stop this administration’s effort to gut it first and then we have to move on to finish the job and make health care a right.”

Biden opened his speech by pointing to this past weekend’s deadly shooting at a California synagogue, as well as the clashes at a 2017 white nationalist and neo-Nazi rally in Charlottesville, Va.

“We saw hate in Charlottesville, we saw it again in Pittsburgh at the Tree of Life Synagogue – the attack – the deadliest in American history on a Jewish community – and we’re reminded again that we are in a battle for America’s soul. I really believe that. And we have to restore it,” he emphasized.

Near the end of his speech, Biden took aim at the president again.

"Everybody knows who Donald Trump is," he says. "We Democrats and we independents who have the same view have to choose hope over fear, unity over division, and maybe most importantly, truth over lies.”

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Biden entered the hall to the Bruce Springsteen song "We Take Care of Our Own," a popular theme of the Obama-Biden 2012 re-election campaign.

Hours earlier, the former vice president landed his first major endorsement, from the International Association of Fire Fighters (IAFF). IAFF general president Harold Schaitberger warmed up the crowd in Pittsburgh as they waited for Biden to arrive.

Soon after the endorsement, Trump slammed the leaders of what he called the “Dues Sucking firefighters” union.

“I’ll never get the support of Dues Crazy union leadership, those people who rip-off their membership with ridiculously high dues, medical and other expenses while being paid a fortune. But the members love Trump. They look at our record economy, tax & reg cuts, military etc. WIN!” Trump tweeted.

Fox News' Peter Doocy contributed to this report.