Aides to Senator Kamala Harris of California say that her fund-raisers in Martha’s Vineyard and the Hamptons this summer have been all about helping Democrats in 2018. Former Vice President Joseph R. Biden Jr.’s allies say his new political group is building an email list so he can communicate directly with his supporters about the future of the party and the country. And Representative Tim Ryan of Ohio says he has been traveling to Iowa and New Hampshire in part because “I like being out around the country.”…

In interviews, more than three dozen leading Democratic donors, fund-raisers and operatives agreed that it was the earliest start they had ever seen to the jockeying that typically precedes the official kickoff to the campaign for the party’s presidential nomination. It is a reflection of the deep antipathy toward President Trump among Democrats, and the widespread belief that the right candidate could defeat him, but also of the likelihood that the contest for the nomination could be the longest, most crowded and most expensive in history.