Democratic President Would Face a Senate Reality Check

Republicans and a handful of moderate Democrats have power to constrain the fate of liberal legislative proposals

Every liberal legislative promise from a Democratic presidential candidate—from Beto O’Rourke’s $5 trillion climate-change plan to Elizabeth Warren’s wealth tax to Bernie Sanders’ Medicare for All idea—comes with an asterisk: the U.S. Senate.

In a Democratic president’s worst-case scenario, Republicans retain control of the Senate in 2020 and Majority Leader Mitch McConnell (R., Ky.) plays the grim-reaper role he relishes, creating a graveyard for Democratic legislation.

But even if Democrats regain the Senate, the fate of environmental, health and tax policy will be constrained by a handful of more moderate Democrats. Even if Democrats change Senate rules to let any legislation pass with a bare majority, they would still likely need to keep both wings of the party satisfied to muster at least 50 votes for their top priorities.

The dynamic is a reminder that the Democratic Party as a whole isn’t necessarily on board with some of the more liberal proposals of the party’s presidential contenders.

“Under the most optimistic scenario, I can guarantee there will be at least a handful of Senate Democrats who will be dead-set against doing what the advocates will be pushing for,” said Jim Manley, an aide to former Senate Majority Leader Harry Reid (D., Nev.) “There’s still a real question about how much you can get done.”

This reality check looms over campaign-trail policy proposals that candidates make a central part of their stump speeches. A Democratic president trying to expand on President Obama’s accomplishments or roll back President Trump’s achievements will find those ideas shaped by the aims of a few senators.

One, for example, is West Virginia’s Sen. Joe Manchin. He voted against Mr. Trump’s tax law, wants improvements to the Affordable Care Act and wants to address climate change.

But he hasn’t sponsored plans for a fully government-run health-care system. He has described his climate-change approach as pragmatic and advocates an all-of-the-above energy policy that reflects the needs of his coal-producing state.

It is early, for sure, but Mr. Manchin—along with Arizona’s Kyrsten Sinema, and Alabama’s Doug Jones, if he survives re-election next year—could find themselves at the Senate’s pivot point. Democrats currently hold 47 seats in the Senate, putting the majority within reach.

Democrats are targeting Republican incumbents in Iowa, Maine, Georgia, Colorado, Arizona and North Carolina and defending Mr. Jones on GOP turf in Alabama. None will be easy, and Democrats need a net gain of three for a majority if they have a vice president’s tiebreaking vote.

To Senate watchers, the moderate in the middle is a familiar story, the unavoidable result of a more sharply partisan legislature. That is where Joe Lieberman, Ben Nelson and others were in 2009. The compromises they struck on health care removed the public-option insurance plan from what would become the Affordable Care Act and forced progressives into other concessions.