The reverse was true in California in 2018. The media convinced gullible California Republicans to nominate carpetbagging flakey loser John Cox (we're very familiar with his quixotic campaigns here in Illinois where he never came close to winning) as their nominee for Governor, saying over and over again that he was "within striking distance" of Gavin Newsom and could "turn California red". They bought it and eagerly nominated him over native Californians with solid conservative histories and a track record of winning elections.
The fall election season thus turned into a non-event for the Dems. Newsom easily won the office without breaking a sweat, and crushed Cox by the second biggest margin in CA history.
I wonder if the people who drank the "Cox can win" kool-aid have buyers remorse over that.
I usually don’t care about polls, since they usually consider 300-500 people. I prefer to predict statewide elections based on how that state voted two years earlier. In 2018, Texas elected a Republican to the U.S. Senate and a Republican for governor. That’s why I know Trump will easily win Texas in 2020.