One stream of recurrent polling is to ask registered voters whether, if the election was held today, they’d vote for a Democrat or Republican for Congress. This is called the “generic ballot” because the identity of the candidate isn’t specified beyond party affiliation. The ABC News/Washington Post Poll has the data.
In the forty years this question has been posed, today Republicans have the highest score they’ve ever attained, at 51%. They lead the Democrats who received only 41%. It is almost another year to the next congressional election, but these numbers have to be cheerful news for the GOP.
Probably the best way to think about the generic ballot numbers is as a proxy for how the party-in-power is current seen. Registered voters’ view of Democrats - led by Biden, Pelosi, and Schumer - isn’t positive.