The Repugs know that, in terms of the Presidency (without their gerrymandering to boost their House seats), demographics are steadily shifting away from them.
Trump put together an electoral coalition of voters in 2016. As well as the Repug loyalists, gun fetishists, racists and religious bigots who want to impose puritanical oppression on everyone, Trump sold his MAGA snake oil to millions of [justifiably] disenfranchised Americans who were economically disadvantaged (principally by corporate offshoring of manufacturing jobs and economic globalisation generally).
By 2020, many had seen through the the MAGA bollocks and abandoned him.
The Repugs know they will struggle to get the numbers for any future Presidential election so need to retain as many of the Trump 'base' as they can. That's why they've been doubling-down on the 'culture war' crap, and throwing red meat to the oppressive religious-right.
They're also acutely aware that they have to publicly support Trump and fight for him, or a chunk of his base with fuck off in a strop.
Privately, I reckon many are hoping he gets convicted and taken out of the picture (they'd make him out to be a martyr and play that card for all its worth)
In the meantime, they increase the polarisation of the US and increase the chances of a major internal conflict erupting there.
They're utter scum.