We went into Election Day with a lot of uncertainty, but we could say with relative confidence that Republicans were the clear favorites to win control of the U.S. Senate. Aided by former President Donald Trump's lead in most (if not all) of the seven crucial swing states, the GOP appears to have accomplished more than just seizing control – the party could have its largest majority in at least a decade, if not even longer, have .

Earlier today, ABC News predicted Republican gains in three states, while Republican candidates hold the lead in two additional seats currently held by Democrats. Additionally, no Republican-held seats are expected to change hands, meaning Republicans should gain at least a four-seat lead in the Senate, with several more opportunities to join the Republican caucus if turnout continues to rise.

Coming into this election, Democrats held a razor-thin majority of 51 seats to 49 in the Senate, supported by the four independents who caucused with them. That meant the GOP needed a net gain of one seat to reach a 50-50 tie — in which case the party that controls the vice presidency would control the Senate — or two seats to gain complete control. Helpfully, Republicans had a number of lucrative choices available to them, including three Democratic-held seats in states that former President Donald Trump held in 2016, 2020 and, as it turned out, 2024. Meanwhile, Democrats had few realistic opportunities to gain ground on the Republican Party. Understandably, the final Senate projection of 538 gave Republicans just over a 9-in-10 chance of winning the chamber.

Republicans secured their 50th seat with their easiest win of the night in West Virginia, where the resignation of Democratic-turned-independent Sen. Joe Manchin sparked a GOP flip in the Mountain State. Popular Republican Gov. Jim Justice appears to have won a landslide victory, leading Democrat Glenn Elliott 69 percent to 28 percent. In a state where Trump has a lead of more than 40 percentage points, this was anything but a surprise.

The 51st seat for Republicans came in Ohio. Republican Bernie Moreno is expected to defeat Democratic Senator Sherrod Brown: With 95 percent of the expected vote, Moreno currently has a lead of 50 to 46 percent. Brown was ahead of Vice President Kamala Harris, who trails Trump 55 percent to 44 percent in Ohio, but the incumbent failed to attract enough Trump voters to keep his seat.

Republicans are also expected to win in Montana, Democrats' third red-state seat. There, Republican Tim Sheehy is about eight points ahead of Democratic Senator Jon Tester, 53 percent to 45 percent (with 88 percent of the expected votes reported). Like Brown, Tester was ahead of Harris, who won only about 38 percent in Big Sky Country.

And it looks like there may be four more seats held by Democrats in play for Republicans. As of this writing, Republican Mike Rogers is narrowly trailing Democrat Elissa Slotkin in Michigan by less than one point, with about 4 percent of the expected vote remaining. In Pennsylvania, Republican Dave McCormick leads Democratic Sen. Bob Casey Jr. by less than a point, 49.1 percent to 48.3 percent, with 4 percent of expected votes still to be counted. In Nevada, Republican Sam Brown is just ahead of Democratic Senator Jacky Rosen with around 88 percent of the expected vote. Republicans could even compete for Arizona, although Democratic Rep. Ruben Gallego leads Republican Kari Lake by about two percentage points, while Trump has a slim lead in the state with more than 60 percent of the expected vote. One bright spot for Democrats: In Wisconsin's contested seat, Democratic Sen. Tammy Baldwin currently has a lead of just under 1 percentage point, with 99 percent of expected votes reported, even as Trump is expected to narrowly carry the state.

As we discussed in our introduction to the Senate forecast in October, the GOP will have a good chance of retaining that majority unless Democrats can win in some places where they have fallen short in recent years. In 2026, Republicans are defending just one seat in a state that Trump is likely to lose in this election (Maine), while only a few other seats are in red states that might be competitive in a midterm election cycle (North Carolina and at least based on 2018, Texas). In 2028, Democrats will then have to defend swing state or potentially competitive seats in Arizona, Georgia, Nevada, New Hampshire and Pennsylvania. Meanwhile, the GOP will only defend two seats this year that appear potentially at risk based on their recent history: North Carolina and Wisconsin.

Some things will inevitably change based on the public's reaction to the next Congress and Trump's second term as president. Democrats may have opportunities that we are not currently seeing. But if Republicans end up with 55 or more seats after this election, it would be their largest majority since reaching 55 seats in the 2004 election.