WASHINGTON (AP) — A tumultuous election season that tugged again at America's searing political divides and raised questions about its commitment to a democratic future comes to a close on Tuesday with top races around the country that will provide a key test of Joe Biden's presidency.

Democrats feared their grip on the U.S. House may be slipping and that their control of the U.S. Senate — once seen as more secure — may loosen. The party's governors in places like Wisconsin, Michigan and Nevada are also staring down serious Republican challengers.

Even Biden, who planned to watch the evening's election returns at the White House, said late Monday night that he thought his party would keep the Senate but "the House is tougher." Asked how that would make governing, his assessment was stark: "More difficult."

All House seats were up for gabs as were 34 Senate seats — with cliffhangers especially likely in Pennsylvania, Georgia and Arizona. Thirty-six states are electing governors, with many of those races also poised to come down to the slimmest of margins.

The GOP is betting that messaging focused on the economy, gas prices and crime will resonate with voters at a time of soaring inflation and rising violence. Ultimately, they're confident that outrage stemming from the Supreme Court's decision to eliminate a woman's constitutional right to an abortion has faded and that the midterms have become a more traditional assessment of the president's performance.

"It will be a referendum on the incompetence of this administration," Minnesota Republican Rep. Tom Emmer, who's running the GOP effort to retake the House, said of the election.

With polls open across most of the country, few major voting problems were reported, though there were hiccups typical of most Election Days. Some tabulators were not working in a New Jersey county and a number of polling places in Pennsylvania were delayed in opening because workers showed up late.

In Philadelphia, where Democrats are counting on strong turnout, people complained about being turned away as they showed up in person to try and fix problems with their previously cast mail-in ballots. But officials said there was still time to reconcile those issues.

And some Arizona voters grew angry and suspicious in the Phoenix suburb of Anthem when they were told that one of the two tabulators at a polling site wasn't working and they'd have to wait up to 30 minutes.

The election could have a profound impact on Biden's next two years. Republican control of even one chamber of Congress would leave the president vulnerable to numerous investigations into his family and administration while defending his policy accomplishments, including sweeping infrastructure legislation along with a major health care and social spending package.

An emboldened GOP could also make it harder to raise the debt ceiling and add restrictions to additional support for Ukraine in the war with Russia.

If Republicans have an especially strong election, winning Democrat-held congressional seats in places like New Hampshire or Washington state, pressure could build for Biden to opt against reelection in 2024. Former President Donald Trump, meanwhile, may try to capitalize on GOP gains by formally launching another bid for the White House during a "very big announcement" in Florida next week.

Voting in Palm Beach, Florida, on Tuesday, Trump predicted that Republicans would have "a great night" on Tuesday and that the upcoming event "would be very exciting for a lot of people."

The former president has endorsed more than 300 candidates running Tuesday and said he voted for Republican Ron DeSantis, who is seeking his second term as Florida's governor. DeSantis is viewed as a potential leading GOP primary alternative to Trump should he jump into the 2024 White House race, as is widely expected.

The midterms arrive as the U.S. is emerging from the worst of the COVID-19 pandemic only to confront sharp economic challenges. The Supreme Court stripped away the constitutional right to an abortion, eliminating protections that had been in place for five decades.

"People recognize that this fundamental freedom has been taken away," said Alexis McGill Johnson, president of Planned Parenthood Federation of America.

"They see this is an economic issue, a health care issue, a freedom issue," McGill Johnson added. "And they're enraged."

It's also the first national election since the Jan. 6 insurrection, meaning the country's very democratic future is in question. Some who participated in — or were in the vicinity of — the deadly attack are poised to win Tuesday, including House seats. GOP candidates for secretary of state in places like Arizona, Nevada and Michigan have refused to accept the results of the 2020 presidential election. That could leave them overseeing future elections in states that are often pivotal in presidential contests.

With only rare exceptions, the president's party loses seats in his first midterm. And Biden's lagging approval left many Democrats in competitive races reluctant to campaign with him.

Only 43% of U.S. adults said they approved of how Biden is handling his job as president, according to an October poll by The Associated Press-NORC Center for Public Affairs Research. Just 25% said then that country is headed in the right direction.

Still, Biden's allies have expressed hope that voters will reject Republicans who have contributed to an extreme political environment.

"I think what we're seeing now is one party has a moral compass," said Cedric Richmond, who was a senior adviser to Biden in the White House and now works at the Democratic National Committee. "And one party wants a power grab."

That message resonated with Kevin Tolbert, a 49-year-old who works in labor law and lives in Southfield, Michigan.

"It is something that has to be protected and we protect that by voting and being out and supporting our country," Tolbert said. "It's a fragile space that we're in. I think it's really important that we protect it, because we could end up like some of the things we saw in the past — dictators and such. We don't need that."

Michael Dupigny, 83, of Washington, wasn't expecting issues, but was to cast his ballot in person, saying he wanted "to see what's happening, with the machines, with the people, to see that everything is working well at the voting station."

Federal and state election officials — and Trump's own attorney general — have said there is no credible evidence the 2020 election was tainted. His allegations of fraud were also roundly rejected by courts, including by judges Trump appointed. But political divisions that have smoldered since 2020 weren't on display everywhere on Tuesday.

Barbara Brown, 76, voted Tuesday in Chestertown, Maryland, east of the state capital of Annapolis, and said she saw Republican and Democratic candidates standing together, holding their campaign signs, "laughing and talking. I was blown away."

Brown noted that it was local candidates showing political civility, "But we'll take what we can get."

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Associated Press writers Corey Williams in Southfield, Michigan, Gary Fields in Chestertown, Maryland, Anita Snow in Phoenix and Claudia Lauer in Philadelphia, Jill Colvin in Washington and Associated Press photographer Jacquelyn Martin contributed to this report.

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Follow the AP's coverage of the 2022 midterm elections at https://apnews.com/hub/2022-midterm-elections. And learn more about the issues and factors at play in the midterms at https://apnews.com/hub/explaining-the-elections.