When will we know who has won the US midterm elections?

• US midterm results may take minutes to weeks, because each state counts and reports votes at different times. Early returns can create a misleading “mirage”.
• Democrats need three more House seats and four more Senate seats to win control. House control would block Trump’s plans and increase oversight; Senate control would shape appointments.
• The Associated Press and TV networks usually make race calls first. But close races, mail-in ballots, provisional ballots and Alaska’s ranked-choice voting can delay final winners.

WASHINGTON – The US midterm elections are on Nov 3. The contest for control of Congress represents the biggest political test yet of US President Donald Trump’s second term. 

The results of each race in the US House of Representatives and the Senate – along with the thousands of other races taking place at the state and local level – could take anywhere from minutes to weeks to become clear.

Administration of elections in the US is decentralised; 50 different state laws govern the contests, and some states further delegate key functions to counties.

But within hours of polls closing, race calls in a few competitive House contests in East Coast states are likely to show whether the “blue wave” of Democratic wins that forecasters expected is materialising.

Exactly how high that wave will crest – and which party gets control of the Senate – will depend on races that will be called later.

And there is a danger that early data could provide a misleading mirage. 

Democrats need a net gain of just three seats to take control of the House, and four for the Senate.

Winning the House is enough to block legislation backed by Trump and bog him down in oversight investigations – and, potentially, impeachment.

Winning the Senate would also give Democrats veto power over Trump’s high-level executive and judicial appointments. 

When do the polls close on Nov 3?

Each state sets its own polling times. The first polls are scheduled to close in Kentucky and Indiana at 6pm New York time (7am Singapore time on Nov 4).

The final precincts – including Adak Island, Alaska, the westernmost polling place in the US – are set to close at 1am New York time on Nov 4.

Voters will be allowed to vote as long as they are in line as of closing time.

And all of these times could be extended by court order under certain circumstances – for example, if specific polling places were inaccessible early in the day. Such exigencies could delay results.

When do states start reporting results?

Most states can start reporting their running counts within minutes after polls close, but there are local complexities.

In Kentucky and Indiana, for example, counties in the Eastern time zone will start reporting vote counts even while voters in the Central time zone are still casting ballots. 

Other states, including Alabama, Alaska, Oregon and South Dakota, typically hold off on reporting any results until all counties have voted.

And in Arizona and Idaho, state laws require officials to wait an hour after polls have closed before reporting any results.

How long will it take to determine who has won?

If the last midterm election in 2022 is any indication, it could take days.

That year, the Associated Press (AP) did not call control of the House until Nov 16 – eight days after the election.

Representative Mike Garcia’s re-election in a California district gave Republicans their 218th seat and a majority. 

If it is a close election in 2026, it will likely come down to California again.

Its mail-in voting system allows ballots postmarked by Election Day to be counted, even if these are not delivered until seven days later.

If Democrats win key early House races, the writing could be on the wall long before the 218th race is called.

One such race is in Kentucky’s Sixth District, a district Trump won by 15 points, but where Democrat Zach Dembo is challenging Republican Ralph Alvarado in a surprisingly close race that the election analysis service Cook Political Report rates as a toss-up. 

Control of the Senate could be uncertain for even longer.

One potential holdup is Alaska, which uses ranked-choice voting to determine the winner.

Voters choose their favourite candidate, but can also select a second-favorite, a third and so on.

If no candidate gets a majority of first-place votes, the candidate with the fewest first-choice votes is eliminated.

Those voters’ ballots are then reassigned to their second choice.

The process repeats until someone secures a majority. But that process cannot happen until Nov 18, after all mail-in ballots are received.

Why does it take so long to determine a winner?

Some votes require more processing time. These include:

• Provisional ballots. A provisional ballot is cast by a voter when there is some question about the validity of their vote on Election Day. It often requires more investigation about the voter’s registration status or precinct. 

• Mail-in ballots. In June, the Supreme Court settled a contentious issue at the heart of several recent election disputes: whether states can count ballots postmarked by Election Day, but received afterwards. They can, the court ruled in a 5-4 decision. Fifteen states allow that grace period, but they have different deadlines and procedures for counting them. One common issue is a lack of signature or another defect. Some states allow voters to “cure” those ballots after the fact, which can take time. Election officials also need to verify that the voter has not also cast a ballot in person.

• Overseas ballots. US military personnel and American citizens living abroad are entitled to vote by absentee ballot under the Uniformed and Overseas Citizens Absentee Voting Act of 1986. But states can have different deadlines for those ballots as well.

How likely is a mirage?

“Red mirage” is the term credited to data scientist Josh Mendelsohn in 2020 to describe the phenomenon of results appearing to favour Republicans at the start before shifting in the other direction.

(Mendelsohn was then chief executive officer of Hawkfish, the political data firm launched by Bloomberg founder and majority owner Michael Bloomberg to support his presidential campaign.)

Today, observers refer to both blue and red mirages. 

Here is why a mirage can happen: Election officials in the US report cumulative vote totals in real time as they count ballots, and the leading candidate can change throughout the night.

Those lead changes produce mirages – the illusion that a candidate is winning based on an unrepresentative sample of votes. 

While sudden changes in reported vote totals have often fuelled conspiracy theories in recent years, they are not new and are not evidence of vote tampering.

Votes are not counted in random order.

Precincts closest to county election offices can get their ballots in first, electronic votes can be counted quicker than paper ballots, and smaller precincts tend to report faster than bigger ones.

Weather, poll-worker fatigue and long lines at polling places can also affect the pace of vote counting in some places and not others.

Those shifts can happen in either direction.

In states where Democratic-dominated early and absentee votes are the first to be counted, for example, the effect is a blue mirage. 

Many of the most competitive Senate races in 2026 happen to be in states that are particularly susceptible to mirages.

In 2024, then Vice-President Kamala Harris had early leads in Iowa, Michigan and Texas before falling behind to Trump after 10pm on election night.

Trump led Maine early before losing the statewide vote. And Kansas and Ohio saw two different lead changes as Trump led, then trailed, then ultimately won.

Who calls the winner?

States certify official results on their own schedules, from about a week after Election Day in Oklahoma to mid-December in California, according to the National Conference of State Legislatures.

Some set no firm deadline at all, and contested elections could continue until Congress is sworn in next January, or even later.

In the November 2020 election, Republican Claudia Tenney of New York was not sworn in as a congresswoman until February 2021.

Some contested races could go to the US House itself to decide.

But voters, candidates and markets want to know the score long before that.

In the absence of a centralised vote-counting agency, the AP has become the most widely accepted authority on who is winning which race, tallying votes for every presidential election since Zachary Taylor won the presidency in 1848.

For 2026, it will call results of about 5,000 races, from statewide races for governor and senator down to state legislators and mayors.

The AP, a news cooperative of which Bloomberg News is a member, is able to do that by positioning 4,600 correspondents at boards of elections across the country.

Those reporters watch the ballots being counted and call in the results as they come in.

The AP also collects data from state and local election agency websites, a process that has allowed for competitors such as Decision Desk HQ (DDHQ) to emerge.

A private company founded in 2012, DDHQ boasts of providing earlier race calls, but has a shorter record of doing so accurately. 

National television networks also make their own race calls based on a variety of data sources.

Those “decision desks” often combine election returns with historical voting patterns and voter surveys like AP VoteCast or network exit polls to call a winner.

That is why they are able to call some races as soon as the polls close, and even before a single vote is counted in some instances.

But they do not declare overall control of the House and Senate until they have called a majority of races for one party.

For the US House, that is 218 of 435 seats.

In the 100-member Senate, Democrats need 51 seats; Republicans need only 50 because Vice-President J.D. Vance holds the tie-breaking vote.

Prediction markets, which offer betting markets on elections that are widely cited alongside polls as indicators of election outcomes, generally do not wait until official results to settle bets.

Kalshi Inc, a leading platform, uses reports from various news organisations, including Bloomberg News.

Its competitor Polymarket uses race calls by AP and networks – and even offers markets on when those race calls will come. 

Could the race calls be wrong?

The AP says its calls are not projections or predictions; winners are declared only when it determines the trailing candidate no longer has a path to victory.

Still, bad data sometimes leads to errant calls.

The AP has had to retract a small number of the thousands of race calls it makes on election night, for an accuracy rate of more than 99.9%.

Most retracted calls happen in low-profile races.

One notable exception: The AP had to retract its call that Representative David Valadao of California had defeated Democratic challenger T.J. Cox in 2018. BLOOMBERG