WASHINGTON, D.C. — Senate Majority Leader John Thune stated he worries about Republicans losing control of the Senate. Thune said in a late August 2026 interview that he is a realist, does not try to sugarcoat things, and thinks it is a competitive environment right now.

The Cook Political Report classified six Republican-held Senate seats as toss-ups or leaning Democratic in September 2026, an increase from three in May 2026. The ratings agency identified the Republican-held seats in Texas, Iowa, and Alaska as toss-ups in its latest assessment. Texas and Iowa moved from Lean Republican to Toss Up in the Cook Political Report ratings.

Republicans currently hold 53 seats in the U.S. Senate. Democrats need to net four seats to win the majority. Democrats are at risk of losing three U.S. Senate seats in the 2026 election.

President Donald Trump won Texas, Iowa, Alaska, and Ohio by double digits in the 2024 election. Despite those margins, the political landscape has shifted. An AP-NORC poll conducted in March 2025 found President Donald Trump's job approval rating at 40%.

Senate Democratic Leader Chuck Schumer stated that Democrats have found new paths to the majority in states like Iowa and Texas. Schumer said Democrats now have multiple paths for the majority and found new states, including Iowa and Texas, which people a year ago were not even paying attention to.

In Michigan, Abdul El-Sayed defeated Haley Stevens in the Michigan Democratic primary for U.S. Senate in August 2026. Nearly $70 million was spent against Abdul El-Sayed during the Michigan Democratic primary contest. Polling aggregates overestimated Abdul El-Sayed's support in the Michigan primary by about 9 points.

No Republican candidate has won a U.S. Senate race in Michigan since 1994. Mike Rogers lost the 2024 U.S. Senate race in Michigan by fewer than 20,000 votes.

The Senate Leadership Fund increased its Michigan advertising investment by $6 million after Abdul El-Sayed won the primary. The Senate Leadership Fund's total spending in Michigan reached $51 million. Republican Representative Jim Jordan stated that things still cost too much and the issue needs to be addressed.

In Maine, Graham Platner withdrew from the Maine U.S. Senate race in July 2026 following a sexual assault allegation, which he denies. Democratic delegates selected Troy Jackson as the nominee for U.S. Senate in Maine in late July 2026. Vice President Kamala Harris received more votes than Donald Trump in Maine in the 2024 election.

Susan Collins and aligned super PACs have spent almost $80 million on the Maine U.S. Senate race. Troy Jackson and Democratic-aligned groups have spent and reserved close to $45 million on the Maine U.S. Senate race since Jackson became the nominee.

In Texas, Ken Paxton defeated John Cornyn to win the Republican nomination for U.S. Senate in Texas. Ken Paxton was previously indicted for securities fraud but was not convicted. James Talarico and allied groups have spent nearly $30 million on advertising in the Texas U.S. Senate race since the May 2026 runoff.

MAGA Inc. spent $10 million on TV and digital ads to support Ken Paxton in the Texas U.S. Senate race. MAGA Inc. held more than $400 million last month.

AdImpact projected $3.4 billion in advertising spending on Senate races for the 2026 midterm campaign in June 2026. AdImpact projected $2.8 billion in advertising spending on Senate races in the fall of 2025. A recent Gallup poll found that Democrats have a roughly 10-point party identification advantage over Republicans.

The Silver Bulletin forecast shows Republicans leading in Iowa, Kansas, and Florida. The RealClearPolitics polling aggregate shows Republicans behind in eight of the nine competitive Senate races in the 2026 cycle. The Republican candidate is leading in the polls in Iowa.

An analysis by pollster Patrick Ruffini found that 3,312 polls underestimated Republicans by an average of 3.7 points over the past four election cycles. The polling error rate for Republicans jumped to 5.9 percentage points in recent cycles according to Patrick Ruffini's analysis. Susan Collins won the 2020 Maine U.S. Senate election by 8.6 percentage points after polling aggregates had her down by roughly 5 percentage points.

Why It Matters

The shift in Cook Political Report ratings indicates a narrowing path for Republicans to maintain their 53-seat majority. With Democrats needing to net four seats and six GOP-held seats now rated as toss-ups or leaning Democratic, the margin for error has diminished. The surge in advertising spending, projected at $3.4 billion for the 2026 cycle, shows the financial intensity of these contests.

Polling discrepancies remain a critical variable. Historical data shows that aggregates have missed margins, such as the 9-point overestimate of Abdul El-Sayed in Michigan and the 5-point underestimate of Susan Collins in Maine in 2020. Patrick Ruffini's analysis of systematic undercounting of Republican support suggests that current polling averages may not fully reflect the electoral baseline.

Timeline

On May 31, 2026, Ken Paxton defeated John Cornyn to win the Republican nomination for U.S. Senate in Texas.

What's New

It is also established that President Donald Trump won Texas, Iowa, Alaska, and Ohio by double digits in the 2024 election.