U.S. President Donald Trump returned to the rally stage on Monday with a slew of attacks on opponent Joe Biden.

Or, rather, on an imaginary version of Joe Biden.

With three weeks left to go in the presidential election campaign, Trump continues to try to frighten voters about supposed Biden policy positions that the former vice president does not actually endorse.

At Trump's first rally since he was hospitalized for the coronavirus, an hour-long performance in Sanford, Florida, the president delivered at least eight false or misleading warnings about what Biden plans to do in office.

Trump said, for example, that Biden would "destroy protections for pre-existing conditions." That's an egregious lie. Biden is running on preserving and strengthening Obamacare, the law that created the protections. Trump himself, conversely, is trying to get the courts to kill Obamacare, and he has not presented any plan to create similar protections if the Republican lawsuit succeeds.

Trump alleged that Biden has "a plan to eliminate U.S. borders." This is nonsense. Biden is proposing a major liberalization of immigration policy, but he isn't seeking to get rid of borders themselves.

Trump also claimed that Biden would "outlaw the private health insurance plans of over 180 million Americans who love those plans." But Biden has been unwavering in his insistence that Americans who have private health insurance would be able to keep it under his administration.

In fact, Biden ran for the Democratic nomination as a forceful opponent of the single-payer "Medicare for All" proposals that would eliminate most private insurance plans. He has instead proposed a "public option" that would allow people to voluntarily enroll in a Medicare-like government insurance program. (There are some legitimate concerns that a public option might reduce the availability of private insurance over time, but it's just wrong to say Biden would "outlaw" private plans.)

Railing against Biden some more, Trump claimed that "he'll ban charter schools." Again, that is not an actual Biden policy. A party unity task force appointed by Biden and former rival Sen. Bernie Sanders recommended a ban on federal funding to for-profit charter schools, but that is not a total ban, and Biden's campaign said in a statement to CNN that he does not oppose "high-performing public charters."

Trump said Biden would "destroy your suburbs." That is, again, absurd; Biden has simply proposed to provide federal support for the creation of affordable housing, in suburbs and elsewhere, and to revive an Obama-era anti-segregation rule Trump has abandoned.

Trump said Biden would "dismantle your police departments." This, too, is baseless. The federal government is not in charge of the size or structure of local police departments, and Biden, who has repeatedly said he opposes the "defund the police" movement, is proposing a US$300-million increase in federal funding for community policing programs.

Trump said Biden "wants to quadruple your taxes." Not even close, according to both Biden himself and independent analyses.

And Trump repeated his claim that Biden "wants to" impose a "draconian unscientific lockdown" that would crush the economic recovery. In reality, Biden has not expressed any desire for a lockdown. He said in an August interview that he would support a lockdown specifically in the event that scientists said a lockdown was necessary to deal with a virus crisis; he then walked that comment back, saying in September, "There is going to be no need, in my view, to be able to shut down the whole economy."

We'll add one caveat. We can't definitively fact check the future, and it is obviously possible that Biden would pursue some policies as president that differed from his campaign promises.

Still, though. There is just no real basis for a whole lot of what Trump is saying about his opponent.