Dozens of interviews with Democratic establishment leaders this week show that they are not just worried about Mr. Sanders’s candidacy, but are also willing to risk intraparty damage to stop his nomination at the national convention in July if they get the chance. Since Mr. Sanders’s victory in Nevada’s caucuses on Saturday, The Times has interviewed 93 party officials — all of them superdelegates, who could have a say on the nominee at the convention — and found overwhelming opposition to handing the Vermont senator the nomination if he arrived with the most delegates but fell short of a majority…

Jay Jacobs, the New York State Democratic Party chairman and a superdelegate, echoing many others interviewed, said that superdelegates should choose a nominee they believed had the best chance of defeating Mr. Trump if no candidate wins a majority of delegates during the primaries. Mr. Sanders argued that he should become the nominee at the convention with a plurality of delegates, to reflect the will of voters, and that denying him the nomination would enrage his supporters and split the party for years to come…

In a reflection of the establishment’s wariness about Mr. Sanders, only nine of the 93 superdelegates interviewed said that Mr. Sanders should become the nominee purely on the basis of arriving at the convention with a plurality, if he was short of a majority.