Trump is losing to Biden by a 5+% margin in a number of battleground states (Minnesota, Wisconsin, Michigan, Pennsylvania) in polls https://www.270towin.com/maps/biden-trump-polling-map so Trump has nothing to lose and everything to gain by debating Biden on JRE. The polls were not wrong about Clinton. Clinton's lead over Trump in the battleground states were within the margin of error. The popular vote doesn't determine victory for presidents. The electoral college does. A 5+% margin in the polls is above the margin of error. The only way the polls can get it wrong is if there is a shy Trump voter effect in the polling. The House went to the Democrats in 2018. Lots of suburban districts flip red to blue. So there is reason to worry for the Republicans.

The Democrats have effectively weaponized the coronavirus against Trump. 67% of independents polled that America's COVID-19 death rate was unacceptable. Trump needs a knockout in the debates to sway independents.

Blame the mismanagement of Andrew Cuomo and other Democratic Governors for the high death rates in blue states. Point out the lower death rates in Red State America. Point to the rising numbers of deaths of despair (suicide, opioid overdose) in locked down blue states as evidence that that the lockdown has hurt people. Point out that the Democrats want young people to sacrifice their future for a generation that has already lived a full life. Point out that Joe Biden and Kamala Harris defends criminals who terrorize the black community like Jacob Blake, Rayshard Brooks, Breonna Taylor and Michael Brown while the Democrats say nothing about the victims of black on black crime in the ghetto.