Republicans are targeting a quintet of senators from conservative states where Trump walloped Hillary Clinton: Montana, Missouri, Indiana, North Dakota and West Virginia. The GOP could amass a filibuster-proof majority by running the table in those states and other battlegrounds.To prevent that, Schumer will need to mine his fellow leaders to accommodate vulnerable Democrats with profoundly different ideologies and political circumstances -- from Wisconsin's Tammy Baldwin, who also was tapped for a leadership spot, to West Virginia's Manchin, who has gone out of his way to align himself with Trump voters this week.

"We have to be careful how we go down this road," Manchin said during a panel discussion at a centrist "No Labels" conference in Washington.Manchin was referring to Senate Democrats' willingness to use the filibuster to try to block Trump's high court pick and cautioned against doing so.

"If my Democrat friends just hunker down and say, 'No, no, and hell no'…I can understand that [Republicans] are gong to say, 'Wait a minute, we have a pretty good person here. We need to give him a fair shot,'" he said. "Those types of things, I hope we're going to avoid before we get into this dysfunction that we've been in."