President Donald Trump has challenged former Vice President Joe Biden to a general election race, telling the former vice president hours after his presidential campaign announcement,“I will see you at the Starting Gate!”

The president appears to see Biden as a legitimate threat and has predicted that he and Vermont independent Sen. Bernie Sanders will end up clashing for the Democratic nomination.

The president took to Twitter on Thursday morning to use, for the second time in nine days, his new derisive nickname for Biden: “Sleepy Joe.” Previously, the president has also called the former VP “Crazy Joe Biden.”

Biden went directly at Trump in that announcement video, posted online by his campaign early Thursday morning, criticizing the president’s response to the deadly violence in August 2017 in Charlottesville, Virginia, sparked by white supremacist rallies there. The former VP zeroed in on Trump’s declaration, after one woman lost her life during a counterprotest, that he believed there were “very fine people on both sides.”

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When he heard Trump utter those words, Biden said, “I knew the threat to our nation was unlike any I’d ever seen in my lifetime.”

“We are in the battle for the soul of this nation,” he said in the video. “I believe history will look back on four years of this president and all he embraces as an aberrant moment in time. But if we give Donald Trump eight years in the White House, he will forever and fundamentally alter the character of this nation, who we are, and I cannot stand by and watch that happen.”

It took the president, who trails the immediate Democratic frontrunner in polls in a hypothetical head-to-head race, a few hours to respond.

“Welcome to the race Sleepy Joe,” Trump tweeted before giving him some advice about battling his 2020 Democratic primary foes and challenging his smarts.

“I only hope you have the intelligence, long in doubt, to wage a successful primary campaign. It will be nasty — you will be dealing with people who truly have some very sick & demented ideas,” wrote Trump, who has taken to publicly accusing most of the Democratic field of being “socialists” who want to dramatically raise taxes and control many aspects of citizens’ lives with a more expansive federal government.

Welcome to the race Sleepy Joe. I only hope you have the intelligence, long in doubt, to wage a successful primary campaign. It will be nasty – you will be dealing with people who truly have some very sick & demented ideas. But if you make it, I will see you at the Starting Gate!

— Donald J. Trump (@realDonaldTrump) April 25, 2019

Trump and Biden have clashed before, once trading barbs about who would win a fistfight. Now the president seems to want to take Biden on in the general election.

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“But if you make it, I will see you at the Starting Gate!” Trump tweeted in a message meant for the former VP. Political analysts on both sides say Biden could appeal to the blue-collar Rust Belt and Upper Midwest voters who broke for Trump last time after voting twice for the Obama-Biden ticket.

Biden jumped into the race one day after the president abruptly ended an impromptu press conference on the White House’s South Lawn with reporters, as he headed to a drug abuse conference in Atlanta with a message for the entire Democratic field.

“They’re not going to win with the people that I see. And they’re not gonna win against me,” Trump said before turning and walking to Marine One. “The only way they can maybe luck out — and I don’t think that’s going to happen — it might make it even the opposite, that’s what a lot of people are saying — the only way they can luck out is by constantly going after me on nonsense.”