The US presidential race draws much of the world’s attention at this moment, only a week before election day. Indeed, the selection of the US president is crucial to shaping foreign and domestic policy over the next four years. However, the makeup of Congress is also important, and — similar to the presidential election — it is a tight race. Every two years, Americans vote for all seats in the House of Representatives. Currently, the Republican Party has a slight majority of seats in the House, which provides the party with significant powers to shape the agenda in the House. Seats in the House are allocated mostly based on a state’s population, so states with larger populations have more seats in the House. This year, the race for the House looks like a toss-up, with either party within reach of gaining a majority. The FiveThirtyEight forecast currently suggests that Republicans are slightly more likely to win the House, but that could change. Often, the party that wins the presidency also wins a majority in the House, but that does not always happen. Seats in the Senate turn over less often than in the House, with senators serving six-year terms, and elections are staggered so that only around one-third of Senate seats are up for election at a time. Currently, Democrats hold a very slight majority in the Senate, which grants them significant powers to shape the Senate’s agenda, but their hold on the chamber looks likely to slip. This year, the race for the House looks like a toss-up Kerry Boyd Anderson Democrats face a short-term challenge and a long-term challenge in the Senate. In the short term, the specific seats that are up for election this year pose a problem for Democrats. With control of the Senate very close, each seat matters. In West Virginia, a long-time Democratic senator (though he recently left the Democratic Party and registered as an independent), Joe Manchin, is retiring, and a Republican is almost certain to replace him. Democratic Senators Sherrod Brown in Ohio and Jon Tester in Montana face difficult races against Republican candidates. In Michigan, Democrat Elissa Slotkin faces a tough race against Republican Mike Rogers; both candidates have expressed support for Israel, but Arab American disillusionment with the Democratic Party over the war in Gaza is one factor weighing down Slotkin. Other races in Pennsylvania and Wisconsin are close. Many political analysts expect the Senate to flip to Republican control, and the FiveThirtyEight model indicates that Republicans have an 88 out of 100 chance of retaking the Senate. The fundamental structure of the Senate combined with long-term shifts in US political trends presents Democrats with a challenge that goes far beyond one election. Under the US Constitution, each state receives two Senate seats, regardless of that state’s population. For example, California has more than 39.5 million people while Wyoming has just over half a million people, but both states have equal representation in the Senate. Therefore, states with smaller populations have disproportionate representation compared to states with larger populations. Demographic and political trends such as urbanization, increased rural identification with the Republican Party, and intensifying partisan polarization combine with the structural reality of the Senate to give Republicans a significant electoral advantage in the chamber. The Democrats’ current slight majority in the Senate might be their last for many years. Seats in the Senate turn over less often than in the House Kerry Boyd Anderson The president has very important powers in the US system, and presidential powers have been increasing for years. Still, Congress also plays a crucial role. Congress makes laws and determines the government’s budget, as well as holding other powers, including investigating the president’s administration. The Senate plays a particularly important role in foreign policy and approving the president’s proposed people to fill key executive and judicial offices. Congress can constrain or enable the president. With an election that is likely to be close and is especially difficult to predict, several scenarios are possible. In 2025, Democratic candidate Kamala Harris could be president with a Democratic-run House to support her and a Republican-run Senate to oppose her. Republican candidate Donald Trump could be president with a fully Republican Congress, including the Senate and House, to support him — or he might have a Republican-controlled Senate, but a Democratic-controlled House. A scenario in which Harris is president and the Democrats control the House and Senate is possible, but unlikely. When a president’s party controls Congress, then the president usually has significant abilities to move forward on his (or her, if a woman is elected president) legislative agenda and faces few, if any, constraints on how he uses the powers of the federal government. A president who faces a Congress that is fully controlled by the opposing party will struggle to accomplish much beyond the limits of executive power — and even then will face constant criticism and investigations. A president with a split Congress has limitations but also significant room to maneuver, but it depends on the president’s and Congressional leaders’ ability and willingness to negotiate and compromise. The outcome of the presidential election will have major consequences for Americans, and for a world that is often directly affected by US foreign and economic policy. However, the outcome of the House and Senate elections will shape the extent to which the president has space to fully pursue his or her agenda. Kerry Boyd Anderson is a writer and political risk consultant with more than 18 years of experience as a professional analyst of international security issues and Middle East political and business risk. Her previous positions include deputy director for advisory with Oxford Analytica. X: @KBAresearch