On Tuesday, voters across the United States will head to the polls to cast a ballot in the 2026 midterm elections.

The race is expected to serve as a referendum on Republican President Donald Trump’s job performance so far, at the halfway mark of his second term.

Maintaining the Republican majority in both chambers of Congress will be key for the success of Trump’s legislative agenda in his final two years.

But control of the US Congress could hinge on a handful of closely contested Senate and House of Representatives races nationwide.

Candidates, political parties and outside groups are pouring hundreds of millions of dollars into the contests, with major political action committees (PACs), including those associated with billionaire tech CEO Elon Musk, fuelling the spending battle. Which races are costing the most, and who is bankrolling the fight for control of Congress? What are the most expensive races? This year’s midterms are projected to break records for the total amount of spending in a political election cycle. The advertising firm AdImpact estimated that $11.21bn has been spent in total for s and reservations as of October 26, compared with $3.2bn for the 2024 presidential election season.

Among the most expensive individual races are those for toss-up Senate seats.

Battles in Texas, Ohio and Michigan rank as the costliest. The race in Texas, for instance, is projected to shatter spending records for a US Senate race.

A Democrat has not won statewide office in Texas since 1994, but Senate hopeful James Talarico aims to break the left-wing party’s losing streak. Nearly every major poll suggests Talarico has a slim lead over his Republican rival, Texas Attorney General Ken Paxton.

CNN, for instance, projected in late October that Talarico had 49 percent support, compared with Paxton’s 43 percent. Interest in the race is high.

The Texas secretary of state’s office released data indicating that nearly 4.5 million Texans cast their ballots in the first week of early voting alone. This election cycle, candidate campaigns and outside groups have spent more than $534m on the Texas race.

Talarico has outpaced his opponent in fundraising.

The Democrat has raised $146m, compared with Paxton’s roughly $22m. However, Paxton has benefitted from significantly more outside spending, with nearly $300m spent on his behalf, compared with about $80m for Talarico. Some $37m for Paxton has come from MAGA Inc, a super PAC aligned with President Donald Trump.

Ohio is considered the second-most expensive Senate race this cycle.

More than $435m has been spent so far on the contest between Democrat Sherrod Brown and Republican Jon Husted. Polls are tight in the Buckeye State.

A Marist Poll released on October 20 suggested Brown was leading Husted by four points, while other surveys showed the two candidates virtually tied. So far, roughly $248m has reportedly been spent on the Republican Husted, compared with $187m on the Democrat Brown.

Michigan has also seen record spending in its Senate contest between Republican Mike Rogers and Democrat Abdul El-Sayed.

An estimated $333m has been spent on that race.

As in Texas, Democrat El-Sayed has led in fundraising but lagged behind his Republican opponent in outside spending. Rogers has raised about $23m, while El-Sayed has brought in approximately $54m.

Outside groups, meanwhile, have spent approximately $169m supporting Rogers and roughly $94m supporting El-Sayed. A late October poll released by Michigan State University has El-Sayed leading Rogers 48 percent to 45.5, but the race is expected to be tight.

How do fundraising totals compare for Democrats and Republicans? Republicans have out-raised – and out-spent – Democrats during this year’s midterm cycle.

According to the FEC’s filings, Republicans have raised more than Democrats since the start of 2025.

That cash advantage was noticeable among the committees that lead each party. For instance, the Democratic National Committee (DNC), which heads the Democratic Party, spent more than it took in.

It raised nearly $252.3m but spent about $252.8m. The Republican National Committee, meanwhile, received about $341m and paid out roughly $303m, as of October 14.

alysis by the publication Politico, which looked at donors from January 2025 through October, found that Republicans are more reliant on large donors, like Musk, as their small-dollar donor base has grown smaller.

Most donations from everyday people, Politico found, have gone straight to Trump, not the candidates.

But it is unclear whether the Republican Party’s fundraising and spending prowess will be enough to counter Democrats’ enthusiasm.

Polls project that the Democratic Party will likely take back the US House and is favoured to control the US Senate as well. Who are the biggest midterm donors? The top donors during this campaign have overwhelmingly backed Republicans. On the right, Tesla and SpaceX CEO Elon Musk gave $446m, and Elizabeth and Richard Uihlein of the shipping supply chain company Uline donated about $150m.

Jeff Yass, founder of the trading firm Susquehanna International Group, and his wife, Janice, also contributed $110m to right-wing causes in the midterm cycle.

On the left, philanthropist George Soros gave about $102m to left-leaning candidates.

Former New York City Mayor Michael Bloomberg also pledged $84.2m to Democrats, with an additional $36m added on Friday. Reid Hoffman, the cofounder of LinkedIn, and his wife, Michelle Yee, gave about $41.2m.

But it is the contribution from the world’s richest person that stands out from the rest. Musk has donated nearly as much as the top six donors – on either side of the aisle – combined.

The bulk of the tech billionaire’s donations, more than $150m, has gone to boost Paxton, the Senate hopeful in Texas, in an effort to help Republicans maintain their Senate majority. The contribution amounts to one of the largest political donations in US history.

Big-dollar donors like Musk have increasingly opted to funnel their money towards Senate candidates as the House appears more likely to come under Democratic control.

Among the Republican-aligned groups, the political nonprofit One Nation has spent $133m. The conservative group was founded by allies of former Republican Senate Majority Leader Mitch McConnell of Kentucky.

The American Action Network, a conservative advocacy group, has spent $64.3m, while the American Prosperity Alliance has spent about $51m.

On the Democratic side, Majority Forward has spent $102m, followed by House Majority Forward at about $93.7m and the Economic Opportunity Fund at $41.5m.