If Democrat Joe Biden wins the U.S. presidency, a divided Congress may prevent him from enacting major priorities like expanding healthcare, fighting climate change and providing aid to millions whose lives have been upended by the coronavirus.
With millions of ballots yet to be counted, Biden led incumbent President Donald Trump in several of the battleground states that will decide the contest.
Yet his Democrats were coming up short in their effort to win control of the Senate, where Republicans currently hold a 53-47 majority, even as they retained control of the House of Representatives.
If those results hold, that would be a recipe for gridlock in Washington, analysts say, where lawmakers would struggle to agree even on basic duties like paying debts and funding government operations.
More ambitious efforts would likely be off the table entirely.
A multi-trillion-dollar plan to curb carbon emissions and create jobs would founder in the Senate.
Biden's plan to raise taxes on corporations and wealthy individuals would also be dead in the water, as would voting-rights and campaign-finance reforms backed by Democrats.
Biden also will likely have to settle for a much smaller economic stimulus package. Democrats have passed several bills out of the House that would provide up to $3.4 trillion to provide assistance to millions of jobless people and help local governments keep teachers, firefighters and other employees on the payroll.
Senate Republicans have so far refused to pass anything at all, though their leader Mitch McConnell said on Wednesday that the two sides needed to find compromise by the end of the year. He did, however, show willingness to meet a key Democratic demand - more money for state and local governments.
"The message from Senate Republicans is going to be: 'The American people elected us to tap a brake on this unrequited socialism that Democrats are going to try to bring to this country,'" said Jon Lieber, a former McConnell aide now with the Eurasia Group.
Lacking a majority on Capitol Hill, Biden could issue executive orders to pursue smaller-bore agenda items, like student-loan relief and consumer protections.
That go-it-alone approach, used by Trump and Democratic President Barack Obama before him, could be easily undone by a Republican successor.
Coronavirus, climate and cabinet
On his first day in the White House, Biden says, he will issue a national strategy to respond to COVID-19 that will likely include a mask mandate and clearer guidance on testing and school reopenings. He has also promised to work more productively with health officials that Trump has ignored, such as Dr. Anthony Fauci, the nation's top infectious-disease expert.
But a Republican Senate could reject Cabinet appointees they deem too liberal, forcing Biden to opt for consensus picks that might frustrate those on his party's left wing.
"We want to make sure that people who are implementing parts of his (climate change) plan are not people who are aligned with the fossil-fuel industry, are not corporate lobbyists," said Garrett Blad, national spokesman of the Sunrise Movement, a grassroots group pushing for aggressive action on climate change.
Biden campaigned as a centrist who would try to work across partisan divides, and as a member of the Senate from 1972 to 2008 has a deep knowledge of its workings and personal relationships with many of its members.
"Look for him to drive long-standing priorities of his like infrastructure, where he could perhaps find support from a moderate Republican or two," said Scott Mulhauser, a Democratic strategist who worked for Biden in the 2012 presidential election.
But many of Biden's former Republican colleagues have retired or been voted out, leaving a more conservative majority that is less inclined to compromise.
"These periods of split-party control tend not to be very productive," said Sarah Binder, a political science professor at George Washington University.
Facing another two years of gridlock, Democrats would likely focus on winning a Senate majority in the next congressional election in November 2022.
But that could turn out poorly for Democrats if Washington does not takes dramatic steps to bolster the economy, improve health-care and curb climate change, said Adam Jentleson, a former Democratic Senate leadership aide.
"The real danger scenario for Biden and Democrats is that Republicans force all of the solutions to be inadequate and Democrats take them because they have to," he said.