Donald Trump was defiant in the face of an impeachment probe during a rally in Minneapolis, Minnesota. The Thursday event was his first since Democrats began proceedings two weeks ago to remove him from office.

Facing an investigation provoked by his unprecedented call for Ukraine and then China to assist in digging up dirt on his political rivals, the president continued to lay into Biden and his son Hunter, whom he and his allies have accused, without evidence, of illegally profiting off his father's office.

The president asked "Where's Hunter?" And he said he wanted to see him because he had some questions for him. He addressed Biden's son in an imaginary monologue: "Hunter, you know nothing about energy. You know nothing about China. You know nothing about anything, frankly. Hunter, you're a loser."

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Mr. Trump went on to say, "Your father was never considered smart. He was never considered a good senator." And he added, "He was only a good vice president because he understood how to kiss Barack Obama's a**."

He spent little time defending his attempt to pressure the Ukrainian president to investigate the Biden. Instead he cast the impeachment fight in simpler basic terms - a battle between him and the "swamp."

"They want to erase your vote like it never existed," he told supporters. "They want to erase your voice, and they want to erase your future."

Mr. Trump was by his own admission fired up and off script as he spoke for more than 90 minutes. Few of his political opponents were spared from insults, including Democratic Representative Ilhan Omar of Minnesota and House Speaker Nancy Pelosi.

The event at the Target Center also showed Mr. Trump's intent to target a state he narrowly lost in 2016 but hopes to win in 2020.

In 2016, Hillary Clinton squeaked out a win by a mere 1.5% in the state. Still, Mr. Trump surpassed expectations in the state, which currently holds the longest record of voting Democratic in presidential elections and was the only state won by Walter Mondale in Ronald Reagan's 49-state landslide in 1984. The last Republican to win Minnesota was Richard Nixon in 1972.

Democratic National Committee Chair Tom Perez said at a meeting in June that if he were Mr. Trump, he would be targeting Minnesota as ground zero. In July, Mr. Trump tweeted that he would win the state in 2020.

A couple of days before the rally, Mr. Trump was fighting on Twitter with Representative Ilhan Omar. The president called on Minnesotans to "dump" Omar and the liberal Minneapolis mayor. Omar responded, "While you spew hate, we will keep fighting for the America we deserve." Mr. Trump has been feuding with Omar for months over her criticism of his administration.

The Trump campaign will have considerably more to work with in financing his attempt to win Minnesota in 2020. His record fundraising enables his campaign to try to expand the number of states he won in 2016. Minnesota is the third state Mr. Trump lost in 2016 in which he is holding a rally. He has already held rallies in New Mexico and New Hampshire.

Ellee Watson, Arden Farhi and Rob Legare contributed to this report.