As American politics becomes increasingly nationalized, fewer voters have showed a willingness to split tickets between one party’s presidential candidate and the other’s candidates for Senate or House seats. In 2016, for the first time since the direct election of senators began a century ago, every U.S. Senate contest broke the same way as the presidential contest in that state.

“What you do in these situations is you localize these races,” said Jai Chabria, a Republican strategist in Ohio. “But that’s a hard thing to do.”

Only a handful of politicians have managed to build an individual brand strong enough to overcome their state’s shifting political tides. But even this year, some of those incumbents — like Collins in Maine — are facing steep headwinds. And for others, it may be too late.

“If you’re trying to disassociate yourself from the president and establish your own brand this late in the race, you’re probably in trouble,” said Ken Spain, a longtime Republican strategist who held senior positions at the National Republican Congressional Committee. “That process needed to have begun months ago, if not years ago.”