I checked 538's updated ratings and the evaluation Rasmussen poll has improved. It used to be a C+ rated poll and now it is B rated.
I found a recent Monmouth poll that includes perceptions about the legitimacy of Biden's win at
https://www.monmouth.edu/polling-instit ... 62121.pdf/. It was conducted June 9 through 14. Results look to me to be consistent with the way things have been on the question in the past. 61% of respondents believed "Joe Biden won the 2020 election fair and square," 32% believed " he only won
it due to voter fraud," and 7% said they didn't know. 90% of Democrats believed he won fair and square vs. 4% who believed he won due to fraud. 36% of Republicans believed Biden won fair and square vs. 57% who believed he won due to fraud.
The Monmouth poll is A rated.
Nevertheless, it is absolutely horrible that such a large proportion of Republicans are so totally out of touch with reality.