President Donald Trump voiced confidence Monday in his ability to win a repeat victory in Pennsylvania in 2020 and took a fresh swipe at one of his leading Democratic rivals, telling rallygoers that native son Joe Biden had abandoned them by representing Delaware in the Senate.

Trump’s Pennsylvania visit, intended to boost Republican congressional candidate Fred Keller over Democrat Marc Friedenberg in a Tuesday special election for an open House seat.

“We’ve got to win tomorrow, Fred,” Trump told a cheering rally crowd at a hangar at Williamsport Regional Airport.

Thousands of people turned out for the rally at the airport hangar, some arriving 10 hours earlier to get a spot. At least three people collapsed from the heat, with others leaving early to get some fresh air.

“I’ll be seeing a lot of you over the next year. I’ll be here a lot,” Trump told an audience of thousands at a local airport hangar. “Got to win this state. We’ve got to win this state. We did great last time.”

Trump’s visit to the key battleground state came two days after Biden held a campaign rally in Philadelphia, and the former vice president wasn’t far from Trump’s mind.

“He’s not from Pennsylvania,” Trump said. “I guess he was born here, but he left you folks. He left you for another state. Remember that, please….He left you for another state, and he didn’t take care of you, because he didn’t take care of your jobs. He let other countries come in and rip off America. That doesn’t happen anymore.”

Trump also referred to the former vice president by the nickname he has coined for him: “Sleepy Joe.”

“Sleepy Joe said that he’s running to, quote, ‘save the world,'” Trump said. “Well, he was. He was going to save every country but ours.”

The president, who spoke in the open air with Air Force One behind him, highlighted the economy’s performance under his leadership and suggested those numbers make him virtually unbeatable.

“Politics is a crazy world, but when you have the best employment numbers in history, when you have the best unemployment numbers in history … I don’t know, how the hell do you lose this election, right?” Trump said. The current unemployment rate of 3.6% is actually the lowest since 1969, when it stood at 3.5%. Unemployment was even lower than that in the early 1950s, and much lower, under 2%, during three years of World War II.

Just last week, Trump introduced a new immigrant proposal that he called pro-immigrant because it welcomes high-educated and high-skilled workers to the country.

“Our country is full,” he said. “We don’t want more people here. Our country is full.”

Keller himself offered a rousing endorsement of Trump, saying he wants to go to Congress to be a vote for the president. Keller told Trump the people of this region of Pennsylvania “have been behind you since Day One, and, Mr. President, our support for you is as strong today as it ever was.”

“In 2016, Pennsylvania put Donald Trump over the top. And in 2020, we’re going to do it again,” Keller said.

Biden is making a big play for his native Pennsylvania, opening his presidential bid in Harrisburg and capping a three-week rollout with Saturday’s event in Philadelphia, the city where he also established his campaign headquarters.