He campaigned on it. Given that he “won” according to his logic, his ideas that he campaigned on are the popular ones.
Only a complete moron would cast a vote for someone (as a vote against his opponent) without even considering who they're actually voting for. Granted, it is possible that when you do that, you could actually be voting for someone who is, in fact, better (by pure dumb luck). But obviously, in the case of the pro-Marxist Harris/biden (who both gleefully support the Marxist BLM/Antifa violent riot organization), it's obviously a far, Far, FAR worse ticket than Trump/Pence. It's not even remotely close.
But that’s how he and the Democrats take it. They won the election, and therefore their ideas are the popular ones.