• Here’s what to watch as results come in. | Get live results here. | Read more analysis here.
Here’s what we know right now
Republicans moved toward expanding their control of the Senate as Democrats took power in the House, with incomplete election results pointing toward a reafirmation of a deeply divided nation.
The G.O.P. flipped seats in three states — Indiana, Missouri and North Dakota — that President Trump had won by a large margin in 2016, and won an open seat in Tennessee. Senator Ted Cruz of Texas held off a surprisingly strong challenge from Beto O’Rourke.
While money and momentum favored the Democrats, the party seized more than a dozen of the 23 seats they need to take the House in early returns. Democrats faced mixed results in the governor’s races, picking up wins in Illinois, Kansas and Michigan, but losing the coveted battleground of Florida.
The returns provided fresh evidence of the partisan split in American political life with Democrats seizing Republican House seats in suburban districts where affluent educated voters had been vocal in their opposition to Mr. Trump.
Results in key Senate races
• Joe Donnelly, one of the most conservative Democrats in the Senate, lost his seat in Indiana to Mike Braun.
• Phil Bredesen, a Democrat and former governor of Tennessee, lost to Representative Marsha Blackburn.
• Senator Ted Cruz defeated Beto O’Rourke, whose underdog campaign mobilized Democrats across the country. Read the story here.
• Senator Heidi Heitkamp of North Dakota lost to Representative Kevin Cramer. Read the story here.
• Two embattled Democratic incumbents held onto their seats: Senator Bob Menendez, of New Jersey, and Senator Joe Manchin of West Virginia.
• Senator Claire McCaskill, a Democrat of Missouri, was defeated by Josh Hawley, the state attorney general. Read the story here.
Key races in Nevada and Arizona are still being tallied.
Kansas has a Democratic governor
Laura Kelly, a Democratic state senator, won the Kansas governor’s race, according to The Associated Press.
Ms. Kelly defeated Kris Kobach, the Kansas secretary of state who is a strong ally of Mr. Trump and is known for his hard-line positions on immigration and voting rights.
Democrats rejoiced when Mr. Kobach won the Republican primary believing his polarizing history would offer them fresh opportunities in the red-leaning great plains state.
It’s not over yet
The Mississippi Senate race advanced to a run-off between Cindy Hyde-Smith, a Republican, and Mike Espy, a Democrat, according to The Associated Press.
The state uses a so-called jungle primary system, where if no candidate reaches a 50 percent threshold, the top two vote-getters face each other in a runoff election. Neither Ms. Hyde-Smith, who was appointed to fill Senator Thad Cochran’s seat, nor Mr. Espy broke that bar. Chris McDaniel, a conservative, failed to make the cutoff.
Their run-off is scheduled for Nov. 27.
Andrew Gillum concedes in Florida
Andrew Gillum conceded the race to Ron DeSantis, handing President Trump an important victory.
Mr. DeSantis, 40, fended off Mr. Gillum, one of the strongest candidates Florida Democrats had fielded in years. Republicans have now won every election for governor since 1998.
Mr. Gillum, who ran a powerful campaign to become Florida’s first black governor, conceded the race after running behind most of the night. “We could not be prouder of the way we ran this race,” he told his supporters. “We recognize that we didn’t win this tonight.” Read the story here.
Democrats pick up key governorships
As expected, Democrats have won a series of governors races, flipping seats in Illinois and Michigan.
Gretchen Whitmer, a former leader in the Michigan State Senate who ran on a slogan of “fix the damn roads,” won the governor’s mansion in Michigan. In one of the country’s most expensive contests, J.B. Pritzker, the billionaire Hyatt Hotel heir, defeated incumbent Governor Bruce Rauner in Illinois. Democrats also held on to governorships in Pennsylvania and New York.
Those are two big victories for the party, which saw its control of statehouses fall to just 16 states during the Obama administration. Results are still coming in for several key statehouses, including Florida.
Because state governments control redistricting, new Democratic governors could help block Republicans from repeating the post-2010 gerrymandering that helped draw congressional districts in their favor.
Mitt Romney is going to Washington after all
The former Massachusetts governor and two-time presidential candidate won the Utah Senate race, according to the Associated Press.
Mr. Romney defeated Jenny Wilson, the Democrat, in his largely uncompetitive race. Moderate Republicans hope he’ll be a check on the president, given his vocal criticism of Mr. Trump during the 2016 campaign. Read more about why he ran here.
A year of firsts
The returns mean a number of historic firsts. Voters chose from a set of candidates that was among the most diverse ever to run in the United States.
Ayanna Pressley, a Democratic in Massachusetts, will become the first African-American woman to represent the state in Congress after winning her race, according to The Associated Press. She beat a 10-term Democratic incumbent in her primary and vowed to pursue “activist leadership” to advance a progressive agenda.
Jared Polis, a wealthy Democratic congressman in Colorado, became the first openly gay man elected as governor in any state after he won his contest, according to The Associated Press. He wants to push for single-payer health care and renewable energy.
Ilhan Omar, a Democratic state legislator in Minnesota, and Rashida Tlaib, a Democratic former state legislator in Michigan, become first the Muslim women elected to Congress after winning their House races, according to The Associated Press.
Ms. Omar will also be the first Somali-American to serve in Congress. She has called for gun control, single-payer health care and a pathway to citizenship for undocumented immigrants.
Sharice Davids, a Democrat and former White House fellow from Kansas, and Deb Haaland, a Democratic community activist from New Mexico, become the first Native American women voted in to the House after winning their races, according to The Associated Press.
Ms. Davids is also the first lesbian Native American to be elected to the House. She has criticized the Republican tax bill and called for “a true tax cut for the middle class.”
In her contest, Ms. Haaland drew parallels between the separation of Native American children and the federal government’s recent border actions.
Representative Marsha Blackburn, a Republican, will be Tennessee’s first female senator after defeating her opponent, according to The Associated Press. She is anti-abortion, and stressed border security and taxes.
Kentucky 6th: Barr fends off McGrath
Representative Andy Barr, an incumbent Republican, defeated Amy McGrath, one of the Democratic Party’s most prominent challengers, according to The Associated Press.
The contest took on national importance as a proxy for whether Democrats could win over white working class voters in rural areas and whether women would rise up against the barbed-wire rhetoric and harsh policies of the Trump presidency.
4 wins for Republicans
House Republicans have successfully defended a few conservative-leaning districts where Democrats saw at least some hope for upset victories, limiting Democrats’ potential gains in Florida’s historically Republican outer suburbs.
Three Republican incumbents — Representatives Brian Mast, Vern Buchanan and Mario Diaz-Balart — held their seats in districts based near Palm Beach, Tampa and Miami, respectively. In a fourth race, Michael Waltz, a Republican, claimed a seat outside Jacksonville left vacant by former Representative Ron DeSantis, who resigned to run for governor.
Democrats were not counting on any of the four districts in order to amass 218 seats for a House majority. But in recent weeks they had seriously contested the Mast and DeSantis seats, especially, and the ease with which Republicans held them may indicate a limit to Democratic inroads in areas with conservative political DNA.
Warren among early calls
Democratic senators in Massachusetts, Delaware, Rhode Island and Connecticut have won their re-election races, as widely expected. The winners include Senator Elizabeth Warren, who spent much of her re-election campaign all but openly running for president. This fall, Ms. Warren said she would “take a hard look” at running for the White House after the midterms are over.
She’s argued that a female president could fix a “broken Washington.”
Exit polls show voter pessimism
Early exit polls reported by CNN on Tuesday night showed a gloomy mood in the country after months of contentious campaigning against a recent backdrop of racial tensions and spurts of violence.
Fifty-six percent of voters said they thought the country was headed in the wrong direction, the cable network reported, with 56 percent disapproving of President Trump, 54 percent disapproving of the Republican Party and 55 percent disapproving of Nancy Pelosi, the Democratic leader in the House of Representatives.
That pessimism belied the positive impression most voters hold about the economy halfway through Mr. Trump’s term. Sixty-eight percent of voters said they believed the economy was in good shape, according to the exit polls, and when it came to personal finances only 14 percent of voters said they were worse off than a year ago. Eighty four percent said their finances were either better off or in the same position.
Mr. Trump has sought to frame the midterm elections as a referendum on his presidency and has campaigned on appeals to law and order and fears over illegal immigration. But exit polls reported by CNN suggested that most voters have been focused on something else: health care.
Forty one percent of voters said that health care was the most important issue facing the country, while only 23 percent cited immigration. The economy was the number one issue for 21 percent of voters, and 11 percent said they were most concerned with gun policy.
Overall, 39 percent of voters said they went to the polls to express their opposition to the president, while 26 percent said they wanted to show support for him. Thirty-three percent said Mr. Trump was not a factor in their vote.
— Liam Stack