“I think people make a mistake when they say that Warren and Sanders are the ones competing in a lane, because the voters that are going to put Warren in a position to be competitive are deciding not between Sanders and Warren, but between Buttigieg, Klobuchar and Warren,” said Addisu Demissie, a Democratic strategist and the former presidential campaign manager for Senator Cory Booker of New Jersey.

“The three of them, I think, are in a fight in a lot of ways for those college-educated voters,” he said.

Mr. Demissie said that Mr. Sanders’s passionate and devoted following made up roughly a third of the Democratic base, and that pulling voters away from him would be nearly impossible. So the other three, he said, would most likely look to “the college-educated, primarily white but not exclusively white voters” to build their support.

In New Hampshire, Ms. Klobuchar narrowly carried the college-educated vote, according to exit polls.

Ms. Klobuchar has cited her steady stream of newspaper endorsements as evidence that she can appeal to those who hope to see a more moderate candidate take on Mr. Trump.

Though only a single metric with unknown impact on voters, to look at the endorsements Ms. Klobuchar has racked up — nine so far, double the amount of most of her rivals — is to get a window into how Ms. Klobuchar long laid the foundation for what appeared to be a very rapid rise from obscurity to winning national delegates.

Sitting in front of largely white and well-educated editorial boards across the country, made up of journalists who often have lengthy résumés of their own, Ms. Klobuchar was able to construct a portrait of her candidacy as one that was built on a bipartisan record in Congress and can appeal to independents.