Washington's new era of divided government begins Thursday as Democrats seize control of the US House, aiming to serve as a check on Donald Trump's disruptive presidency at least until the 2020 election.
Battle-tested Nancy Pelosi will in all likelihood win the gavel as speaker of the House of Representatives, a dramatic return to national power for the California Democrat who made history a dozen years earlier as the first woman to lead the chamber.
She will take command during a period of American political upheaval, and with a caucus riding high after a very strong midterm election showing last November.
Thursday brings an end to Trump's one-party rule in Washington, a massive boost for Democrats who felt deflated after Trump's 2016 victory.
Progressives will be eager to push back with greater effect against an administration they believe has overstepped its authority and abused power in the nearly two years since Trump's inauguration.
They will have that opportunity, as congressional panels will be led by chairmen who have pledged to probe topics such as Trump's income taxes, his firing of attorney general Jeff Sessions, and the president's ties to Vladimir Putin.
Incoming chairpersons have signaled that Trump will face a barrage of probes that could bog down a White House already besieged by Special Counsel Robert Mueller's Russia collusion probe, draining energy from the administration's agenda and foiling Trump's message.
"It's on," Democrat Hakeem Jeffries, a new member of House leadership who is seen by some as a potential future House speaker, tweeted Wednesday.
"Tomorrow, we seize the majority. Then, we pass legislation to end reckless #TrumpShutdown," he added. "Next, we fight to lower healthcare costs and enact a progressive agenda."
While the "blue wave" swept dozens of House Republicans out of Congress last November, Trump's party managed to modestly expand its majority in the Senate to 57-43, meaning Washington gridlock is almost certain to deepen.
Among the first tasks of the 116th Congress will be ending a nearly two-week government shutdown that has left one quarter of federal agencies shuttered due to lapsed funding.
Pelosi has introduced new measures that would fund the agencies, but she noted that they "contain no new wall funding," a move the White House -- and leaders in the Republican-controlled Senate -- dismissed as a non-starter.
"Democrats will have to get serious about border security so that a government funding agreement may be reached that can pass the House, earn 60 votes here in the Senate, and receive a presidential signature," Senate Majority Leader Mitch McConnell said in a statement.
"All three of these things are needed. One partisan vote in the House tomorrow won't solve anything." The House and Senate gavel into session Thursday at noon (1700 GMT), with the new Congress sworn in shortly thereafter. Pelosi is expected to win her speaker election in the early afternoon.
She will preside over the most diverse Congress in history. One hundred House freshmen will take the oath of office, including trailblazers like New York's Alexandria Ocasio-Cortez, who at 29 was the youngest woman ever elected to Congress.
The first two Native American women and first two Muslim women were also elected. The House and Senate will each have a record number of female members come Thursday.
Democrats will move early to protect coverage for people with pre-existing conditions, a popular feature of the Affordable Care Act that a judge in Texas recently struck down.
House Democrats are thumbing their nose at Trump by establishing a special committee on climate so the government can better respond to the urgency of global warming.
Hovering in the background in Washington will be the threat of impeachment, and it is almost certain that some Democrats will introduce proceedings to remove Trump from office.
Even if Democrats believe some of Trump's actions clear the threshold of "high crimes and misdemeanors," Pelosi has downplayed the prospects of impeachment.
"It would be very divisive," she told Elle magazine. "It's not something that I'm stirring the pot on.