Trump’s advisers have long believed he could recover if he could drag Biden’s favorability ratings down. Confronting an opponent who is viewed more favorably than Hillary Clinton was in 2016, Trump is laboring not only to depict Biden as mentally unfit – but as an addled tool of the Democratic Party’s most extreme fringe.

The effort to yoke a centrist Democrat to an “unhinged left” was road-tested in Oklahoma, where Trump mocked Biden as “a helpless puppet of the radical left.” Among the lessons of Tulsa, which will inform countless rallies in the months ahead, was that invoking lightning rod progressives such as Rep. Alexandria Ocasio-Cortez draws a more fervent response than criticizing Biden in isolation — and that linking Biden to that wing of the party is Trump’s lodestar.

“He believes that he has to push Biden to the left, and I think that’s correct strategically,” Frank Luntz, the veteran Republican consultant and pollster, said in an email. “If Biden is seen as a centrist, he’ll have an advantage among swing voters who don’t want to support an extremist. But if he’s seen as left-wing ideologically or overtly partisan, swing voters will have a problem with him.”