South Dakota Senate 2026

Projected figures based on South Dakota partisan lean. Trump won the state by 26 points in 2024. No major Democratic challenger has announced. Figures to be updated as the race develops.

John Thune grew up in Murdo, a small town of fewer than 700 people in the heart of the South Dakota plains, where his father was a WWII veteran and local official. He attended Biola University on a basketball scholarship and earned a graduate degree from the University of South Dakota. He served in the Bush administration at the Small Business Administration before running successfully for Congress in 1996, representing South Dakota’s at-large House seat through 2003.

Thune’s defining political moment came in 2004 when he challenged Senate Minority Leader Tom Daschle. Daschle, one of the most powerful Democrats in Washington, had held his seat since 1987 and was considered nearly unbeatable in a state with a tradition of electing senior senators regardless of party. Thune defeated him by 4,508 votes — less than 1 percentage point — in a race that sent shockwaves through American politics and signaled the deep realignment of rural Great Plains states toward Republicans.

Since then, Thune has won re-election twice by overwhelming margins (by 33 points in 2010, by 28 points in 2016) and climbed steadily through the Senate Republican leadership structure. He served as Republican Conference Chairman, then as Senate Majority Whip under McConnell, before being elected Majority Leader in November 2024. His 2026 re-election would be only his fourth Senate term, but he is already the most powerful Republican senator in terms of institutional position.

The Senate Majority Leader is the most powerful position in the Senate, controlling the chamber’s floor schedule, bill sequencing, committee referrals, and the overall legislative agenda. The Majority Leader sets the pace of Senate action, negotiates with the White House and House Speaker on legislative packages, and serves as the public face of the Republican caucus in the upper chamber.

Thune succeeded Mitch McConnell, who held the position for 18 years and developed a reputation for procedural mastery and a willingness to make maximally partisan tactical decisions — most notably blocking the Merrick Garland Supreme Court nomination in 2016 and then confirming Amy Coney Barrett days before the 2020 election. Thune’s style is generally described as more collegial and less combative than McConnell’s, with a stronger emphasis on traditional legislative procedure and member relationships.

In the first months of his majority leadership, Thune has faced the challenge of managing a narrow Republican Senate majority while coordinating with a Trump White House whose priorities and style sometimes diverge from traditional Senate Republican governance. The 2026 Senate election results will either strengthen or weaken his hand significantly, and his own re-election in South Dakota, though certain, is part of the broader picture of the Republican majority’s durability.

Thune’s relationship with Donald Trump has been one of the defining tensions of his recent career. He was one of the first prominent Republicans to call on Trump to accept the results of the 2020 election, and he voted to certify the Electoral College results on January 7, 2021, the morning after the Capitol attack. Trump repeatedly attacked Thune by name on social media and actively sought to recruit a primary challenger against him in South Dakota for the 2022 cycle — a challenge that never materialized at a serious level.

When Thune ran for Majority Leader in late 2024, Trump initially preferred Rick Scott for the role and expressed skepticism about Thune. Thune won the leadership vote anyway, reflecting that Republican senators — even in a thoroughly Trump-aligned caucus — valued his institutional competence and relationships over Trump’s preferences in an internal leadership race. Since becoming Majority Leader, Thune has worked to maintain a functional relationship with the Trump White House while preserving the Senate’s institutional prerogatives.

This balance — loyal enough to work with the president, independent enough to maintain Senate credibility — is one Thune has navigated carefully. In South Dakota, where Trump won by 26 points, being seen as anti-Trump would be politically damaging. But Thune’s brand has always been more about good governance and constituent service than ideological populism, and South Dakota voters have consistently rewarded that approach.

South Dakota is a sparsely populated Great Plains state with an economy built on agriculture (corn, soybeans, wheat, cattle), tourism centered on the Black Hills and Mount Rushmore, and a growing financial services sector that has benefited from the state’s favorable banking laws. The state’s population of roughly 900,000 makes it one of the smallest states, and its two Senate seats represent a significant per-capita overrepresentation of power in Washington — something Thune’s Majority Leader status amplifies enormously.

The state was once competitive at the Senate level, electing Democrats like Tom Daschle, Tim Johnson, and George McGovern for decades. The realignment that swept rural America beginning in the Obama era completed itself in South Dakota by the 2014 election cycle. Today the state is solidly Republican at every level — both Senate seats, the House seat, the governorship (Kristi Noem), and the state legislature are all Republican.

South Dakota’s key political concerns include agricultural trade policy (tariffs on soybeans and corn affect farm income directly), water rights on the Missouri River, Native American affairs (several large reservations, including Pine Ridge and Rosebud, are within the state and represent both political and policy complexity), and the status of Ellsworth Air Force Base, which Thune has worked to protect from closure.