WASHINGTON (Reuters) - Americans head to the polls on Tuesday in midterm elections that will decide control of Congress for the final two years of President Donald Trump's term.
The results will serve as the first nationwide verdict on Trump's presidency, revealing whether voters want to check the Republican president's power by giving Democrats control of one or both chambers of Congress or are willing to accept the status quo despite frustrations over the cost of living and the US-led war with Iran.
The outcome could also reshape debates within both parties over which messages and policies resonate most with voters ahead of the 2028 presidential election.
Here are six things to watch on Election Day.
THE RACES THAT WILL DECIDE CONTROL OF CONGRESS
Democrats need a net gain of four seats in both the US House of Representatives and US Senate to overturn Republicans' narrow 218-214 and 53-47 majorities.
They are widely expected to reclaim the House, but the Senate battle remains highly competitive. The scale of Democratic gains in one or both chambers will shape Trump's ability to advance his agenda.
Democratic wins in one or both chambers will likely trigger investigations into ethics of Trump and his administration, their handling of immigration enforcement and the Iran war.
A stronger-than-expected Republican showing could reinforce Trump's grip on the party. Heavy losses could increase pressure to rethink unpopular policies such as tariffs and the war while shaping the message of candidates vying to succeed him.
Early results from Republican-held House seats in Florida and Virginia could provide clues to the size of any Democratic gains. Victories in competitive districts would point to a solid Democratic night, while wins in more Republican-leaning areas could signal a much broader backlash against Trump and his policies.
The close Senate fight will likely hinge on six to eight races. Democrats need to flip several Republican-held seats in states Trump carried by double-digit margins in 2024, including Ohio, Iowa, Alaska and Texas.
Even Kansas, despite Trump's 16-point win there, has become competitive in recent weeks and a Democratic victory would signal a broader wave.
Republicans can retain control by winning most of those contests, while Democrats will likely need to hold Michigan and pick up Maine.
PROBLEMS AT THE POLLS AND VOTE COUNT
Election officials have warned close races could spark disputes over voter eligibility, ballot counting and certification, while long lines, machine malfunctions or challenges by partisan poll watchers could fuel litigation and delay results.
Trump's Justice Department plans to deploy about 1,000 monitors nationwide on Election Day, roughly triple the number used in the last midterms, a move some local officials worry could intimidate voters, although the DOJ says those fears are baseless.
Some election officials and legal experts fear federal investigations and legal challenges could delay or disrupt certification of election results in close races.
On October 22, Trump's Justice Department sued to preemptively block Alaska from certifying the results of its Senate race if the Republican incumbent candidate loses by a narrow margin, saying voters could be confused because two Republicans on the ballot have almost identical names.
Attorney General Todd Blanche on October 22 declined to rule out Justice Department intervention in state election certifications, saying extreme circumstances could warrant action.
Several states are also unlikely to produce complete results on election night, especially in close races, providing fertile ground for disputes.
TRUMP'S RESPONSE TO THE RESULTS
How Trump responds to the results, especially if Republicans lose control of Congress, could become one of the night's biggest stories.
In the early hours of November 4, 2020, before vote counting had finished in several states, Trump declared victory and called for counting to stop.
He ultimately lost to Democrat Joe Biden but continued to falsely claim the election had been stolen, helping fuel the January 6, 2021, attack on the US Capitol by a mob of his supporters who were seeking to stop certification of Biden's win by Congress.
Trump still falsely claims he won the 2020 election and has cast doubt on the integrity of these midterms, raising the prospect of Republican challenges if the party loses one or both chambers.
This year, the Trump administration has pressed states for voter data and launched investigations into noncitizen voting, which election experts and studies have found little evidence to support. It recently sued California over alleged noncitizen ballots.
TURNOUT
Turnout by the parties' core supporters will be important. Opinion polls showed Democrats significantly more enthusiastic about voting than Republicans heading into Election Day.
But strategists caution that Democratic constituencies including young, Black and Hispanic voters have historically turned out at lower rates in midterm elections than in presidential years.
Surveys show persistent skepticism among these groups towards both parties, especially over the cost of living. If turnout among those groups falls short of expectations, Democrats could underperform on Election Day.
Early voting data in states that register voters by party showed higher Democratic engagement. But Republicans argue that many of their supporters traditionally wait until Election Day to vote.
WHAT DO RESULTS MEAN FOR THE 2028 RACE?
After their bruising defeat in the 2024 presidential election, Democrats have been split between those arguing for a more populist economic message and those favoring a centrist approach aimed at winning back swing voters.
Strong performances by moderates and left-wing candidates on Tuesday will allow both factions to claim validation of their policies. That could set the stage for a crowded and potentially contentious contest for the party's 2028 presidential nomination.
DID REPUBLICANS' MONEY ADVANTAGE PAY OFF?
Republicans had a significant financial advantage and flooded the airwaves with ads attacking Democratic candidates.
While some Democrats matched or outraised their opponents, Republicans held an overall spending edge of several hundred million dollars once party committees and outside groups were included.
A key question is whether that advantage helped sway tight races, or whether voter concerns over high prices and the Iran war mattered more.
Trump spent more than $277 million, mostly through his MAGA Inc. super PAC, on a late TV and direct-mail blitz to aid struggling Republican candidates, according to Federal Election Commission data.
Tesla CEO Elon Musk spent roughly $366 million during the midterm cycle, including $276 million since July, to support Republican candidates.