Chip Somodevilla/GettyOn Tuesday, voters across the United States will cast their votes in the 2026 midterm elections. All 435 seats in the House of Representatives and 35 of the 100 seats in the Senate are on the ballot.Forecast models give Democrats about a 95% chance of winning a majority in the House. The Senate is a closer race, but Democrats go into Election Day with the edge.But the vote itself may not be the end of the story. Earlier this year, more than a dozen election officials from both parties said they feared President Donald Trump was laying the groundwork to undermine the midterm results. And according to a recent survey, seven in ten Americans doubt Trump will accept the results if his party loses.So, what tools might Trump use to contest or disrupt the results? And are US institutions equipped to withstand interference from the president?A watershed momentWhile Trump himself is not on the ballot, the stakes of these elections are high. The president faces mounting pressure at home, particularly on rising inflation and a deeply unpopular war with Iran.With Election Day fast approaching, Americans have already headed to the polls in droves. According to the University of Florida’s Election Lab, more than 54 million votes have been cast in early voting.A Democrat-controlled House could open investigations, issue subpoenas and stall the president’s agenda for the rest of his term. Republicans want to keep control of both chambers to keep pushing through Trump’s agenda, including the president’s top legislative priority, the SAVE America Act. This would require voters nationwide to show photo identification and proof of citizenship to cast a ballot.What powers does Trump have?On paper, there is very little a president can do to interfere in elections. The US Constitution lets states set the “times, place and manner” of congressional elections, and only Congress can change those rules. The president’s only role is signing or vetoing election laws.What the president does control is the federal government, which includes the Department of Justice (DOJ), Federal Bureau of Investigation (FBI), Department of Homeland Security and the Postal Service. He can direct these agencies through executive orders, but an executive order cannot override state election law.Courts agree. In June, a federal judge permanently blocked most of Trump’s first election-related executive order, which would have forced people to show documents proving citizenship when registering to vote.Also in June, the Supreme Court ruled states can keep counting mail ballots posted by Election Day that arrive later.But the agencies he does control still give him ways to apply pressure at three critical points: voting, counting and certification.Three pressure pointsThe first pressure point is voting itself. In March, Trump ordered the Postal Service to refuse to deliver mail ballots to voters missing from a list states would have to submit. But a federal judge blocked this move, and the Supreme Court subsequently upheld this decision, so mail voting will go ahead unimpeded.The DOJ has announced it will be sending about 1,000 election monitors to all 50 states, its largest effort ever. However, these monitors can only enter polling places with local officials’ permission.A second pressure point is the count. The DOJ has demanded full voter rolls from 49 states and the District of Columbia. It planned to check them against a Homeland Security database to find non-citizens. It has sued 30 states, and no court has ruled in the DOJ’s favour. Last month, a judge struck down the policy nationwide.The third pressure point is certification, which is the formal sign-off on election results by state and local officials. Trump says he will accept the outcome “if they’re honest elections”. If Trump disputes the results, the pressure will fall on these officials to certify them, as it did in 2020 when he pushed Georgia’s top election official to “find” him votes. More drastic measuresSome options for disrupting the outcome of this election are more extreme. The last step in this process will come on January 3 2027, when the new House is sworn in. The Constitution makes each chamber the judge of its own members’ elections. Some fear that Republicans could refuse to seat Democratic winners. The House last refused to seat a certified winner in 1985. However, House Speaker Mike Johnson – the top Republican in the House – has called the idea of going down this road “absurd”.The most extreme option would be for Trump to declare a national emergency. A leaked draft executive order proposed declaring one over alleged foreign interference, then banning most mail ballots and forcing voters to re-register in person. It relies on unfounded claims about foreign interference and voting machines similar to those Trump made in July. Trump said he had never heard of the draft, and legal experts say the laws it cites give no such power to the president.What checks and balances are in place?Each pressure point meets a check. The first is that there is no national election system for a president to take over. Thousands of officials from both parties run the vote, and many have spent months planning for possible federal interference.The courts are the second check. They have already struck down Trump’s attempts to prevent the delivery of mail ballots and blocked the DOJ from obtaining full voter rolls.The third check is Congress itself. Two lawmakers, Democrat Josh Gottheimer and Republican Don Bacon, are asking House members to pledge to seat every certified winner. They hope their pledge will make it harder to justify blocking the swearing-in of any winners come January 3.What to watch forThe first signs of potential interference will come on election night. Some states count mail ballots last, so early leads can shift in the days after polls close. Claims of fraud or victory before the count is finished would be a warning sign.In the days that follow, observers will also watch whether the DOJ presses its cases against California, Washington and Alaska over alleged non-citizen voting, and whether federal agents will try to seize ballots or records.Then comes certification. Most states sign off on results by late November or early December. Counties certifying on time, without court orders, would show the system is working. The last marker is January 3, when every certified winner should be sworn in.So, the clearest test will come in the weeks after Tuesday’s election: will the president prove his critics right, or will he accept the verdict of voters?Jean-Nicolas Bordeleau does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.