For years they dominated the party, brandishing their powerful financial network and global fame to pick favorites for primary elections and lift Democrats even in deep-red states. They were viewed as a joint entity, with a shared name that was the most powerful brand in Democratic politics: the Clintons.

But in the 2018 election campaign, Hillary and Bill Clinton have veered in sharply different directions. Mrs. Clinton appears determined to play at least a limited role in the midterms, bolstering longtime allies and raising money for Democrats in safely liberal areas. Her husband has been all but invisible.

And both have been far less conspicuous than in past election cycles, but for different reasons: Mrs. Clinton faces distrust on the left, where she is seen as an avatar of the Democratic establishment, and raw enmity on the right. Mr. Clinton has been largely sidelined amid new scrutiny of his past misconduct with women.

Mrs. Clinton is expected to break her virtual hiatus from the campaign trail this week, when she will endorse Gov. Andrew M. Cuomo of New York in a contested Democratic primary, her spokesman, Nick Merrill, confirmed — a move sure to enrage liberal activists seeking Mr. Cuomo’s ouster at the hands of Cynthia Nixon, the actress turned progressive insurgent. Mrs. Clinton has also recorded an automated phone call endorsing Stacey Abrams, the former Democratic leader in the Georgia House, who is competing for the party’s nomination for governor on Tuesday.