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 as voters cast ballots in the first national election of Joe Biden’s presidency.

With polls open, Democrats were braced for disappointing results, anxious that their grip on the U.S. House may be slipping and that their hold on the U.S. Senate — once seen as more secure — has loosened. The party’s incumbent governors in places like Wisconsin, Michigan and Nevada are also staring down serious Republican challengers.

Returning to the White House on Monday night after his final campaign event, Biden said he thought Democrats would keep the Senate but acknowledged “the House is tougher.”

The GOP was optimistic about its prospects, 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.

The results could have a profound impact on the final two years of Biden’s presidency. Republican control of even one chamber of Congress would leave Biden vulnerable to a slew of investigations into his family and administration while defending his policy accomplishments, including a sweeping infrastructure measure 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 Democratic 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.