– Democratic senators running for re-election in red states where President Donald Trump remains popular face an agonizing choice over his coming Supreme Court nominee: Vote to confirm the pick and risk demoralizing Democratic voters ahead of the midterm elections, or stick with the party and possibly sacrifice their own seats — and any chance at a Democratic majority in 2019.

The actions of a handful of Senate Democrats struggling to hold their seats in those states — notably Heidi Heitkamp of North Dakota, Joe Donnelly of Indiana and Joe Manchin of West Virginia — will have broad implications for the party at a critical political juncture.

A decision by one or all of them to try to bolster their standing with Republican-leaning voters in their states by backing the president’s nominee would undermine Democratic leaders as they try to sustain party unity. And if their votes put the president’s choice on the court, it could hasten the move to the left by the party’s aggressive activist core, while intensifying the clamor for new, more confrontational leadership.

But if they hold together on a “no” vote, those senators could not only surrender their own seats, but by expanding the Republican majority, they could also narrow the path of Democrats to a Senate majority for years to come by ceding those states to Republicans.

“It is a terrible vote,” Jennifer Duffy, a longtime nonpartisan analyst of Senate races for the Cook Political Report, said about the showdown, which will escalate Monday with the scheduled official announcement of the nominee.

It could not come at a worse time. A final confirmation vote will probably be called just weeks before an election in which Democrats are defending a sprawling battleground, including 10 states carried by Trump, with Democratic pickup opportunities in only a handful of states. A failure to hang on to nearly all 10 would make a Senate takeover very difficult.

The situation is complicated by the fact that Republicans last year denied Democrats the ability to filibuster a Supreme Court candidate, a tool that would have enabled the most vulnerable Democrats to side with the president even as the rest of the party held the line against the nominee and satisfied anxious liberal voters.

In the run-up to his announcement, Trump has sought to intensify the pressure on Democrats who are on the ballot in Republican-leaning states.

“You deserve a senator who doesn’t just talk like he’s from Montana,” Trump said Thursday night during a combative stop in Great Falls, Mont., as he assailed Jon Tester, the conservative state’s two-term Democrat. “You deserve a senator who actually votes like he’s from Montana.”

The president delivered a nearly identical attack on Heitkamp a week earlier in Fargo, N.D., in what appears destined to become a stock line as Trump visits Senate battlegrounds.

Republicans have a history of elevating the Supreme Court above all else, given its influence on major social policy such as abortion, immigration, education, voting rights and the environment.

“For Republicans, the Supreme Court is their biggest voting issue,” said Duffy, the Senate elections analyst. “What this does is it wakes up the base.”