“Historically, endorsements have proven pretty predictive of who wins presidential nominating contests. Since the modern primary era began in 1972, there have been 17 Democratic or Republican primary fights that did not feature an incumbent president. The candidate with the most endorsement points3 on the day before the Iowa caucuses won 11. That’s a better track record than polls have at the same point in the election: Since 1972, the leader in national polls4 on the day before Iowa has won the nomination just 10 out of 17 times.
Twelve of those 17 times, the same candidate led in both endorsements and polls. And of those 12, nine times the candidate won. But the five times that the endorsements and polls disagreed, the endorsement leader won twice, and the polling leader won only once. The other two times, a third candidate won.
It’s a small sample size, but endorsements have an even stronger track record when you filter out the years when the endorsement leader didn’t have all that many endorsements. For example, when the endorsement leader has earned at least 15 percent of the total estimated available endorsement points by the day before the Iowa caucuses,5 that candidate has won their party’s nomination nine out of 10 times. Then-Sen. Hillary Clinton in 2008 is the only exception.”
https://fivethirtyeight.com/features/trump-2024-endorsements-polls/