President Trump says most voters support his attack on Iran even as gasoline prices climb

The likelihood of Democrats taking both chambers of Congress in November's midterm elections has risen to a new high of 66%, according to one prediction market.

Democrats have for months been widely expected to gain control of the U.S. House of Representatives in this November's midterm elections, but now they're increasingly being viewed as likely to take the Senate, too.

The minority party's chance of winning both chambers of Congress has climbed to a new high of 66% this week, as shown in the chart above, which features the latest figures from prediction market Polymarket. (Polymarket has a data partnership with MarketWatch's publisher, Dow Jones.) Another prediction market, Kalshi, was giving a similar likelihood on Wednesday of 64%.

Analysts are expecting losses for President Donald Trump's Republican Party in the midterms in large part due to voters' frustrations with the elevated cost of living. An Ipsos poll last month found that the cost of living was the single most important issue for voters in this year's election, with 47% pointing to it, ahead of concerns about democratic values and norms at 22%, immigration at 12% and crime at 4%.

Voters have been saying they're feeling more financial pain particularly when they fuel up their cars and trucks. A Fox News poll earlier this month found 61% of voters view gasoline prices as a major problem, up from 48% two years ago. The chart below shows how the average price of gas has climbed to around $4.50 per gallon, while diesel has jumped to $6.50 per gallon.

Fuel prices have climbed since January 2025. Such a rise is historically associated with more midterm-election losses for the incumbent party, according to Morgan Stanley.

The incumbent party tends to lose more races in midterm elections when pain at the gas pump is on the rise. Since 1978, midterm cycles in which gas prices climbed from January of the prior year through October of the election year saw the incumbent party lose an average of 32 House seats, Morgan Stanley analysts said in a note last month. When gas prices fell, the average loss was only six seats. Republicans currently have a 219-214 majority in the House, along with a 53-47 edge in the Senate.

Democrats' chance of winning both chambers is increasing, as polls this month for closely watched Senate races have shown leads for their party's candidates, even in red states like Alaska, Iowa, Kansas and Texas. In addition, more voters are expressing disapproval of Trump's performance in office. A RealClear Politics average of polls shows 59.5% of voters disapprove as of Wednesday, marking a new high.

To be sure, prediction markets aren't that reliable. They got the 2022 midterms wrong, forecasting a red wave before voters delivered a red ripple. Prediction markets can also get caught up in narratives and be skewed by flawed or even fraudulent polls. They can also be moved by whale trades.

One nonpartisan forecasting firm, the Cook Political Report, said Wednesday that the fight for the Senate is a "true coin flip," meaning each party has an equal chance of controlling the chamber.

Trump, for his part, has argued that a majority of Americans are willing to put up with the higher fuel prices that have come as a result of his war against Iran.

"I think most people, if they had a vote on lower gas prices or letting Iran have a nuclear weapon, I'd be willing to vote that it would be a massive landslide. People don't want to have Iran have a nuclear weapon," the president told reporters last week.

On Tuesday, Trump endorsed the idea of a ban on U.S. diesel exports, saying a decision on that will come quickly. Analysts have warned that such a ban would raise diesel prices rather than lower them.

What Democratic control of both chambers could mean

Having the Republican Party lose its grip on both chambers of Congress would be a significant setback for Trump.

"Trump will find that a large swath of his agenda will be more scuttled without control of Congress," Libby Cantrill, head of public policy at bond giant Pimco, said in a note on Monday. "While Trump uses executive authority generously, remember that executive orders are only a reinterpretation of existing law, not a changing of the law (which requires Congress), and many of his interpretations have been found illegal in the courts."

She continued: "More oversight will occur if Democrats take the House, but it will be even more acute if the Senate flips. Democrats will have subpoena authority and full control of committee agendas and floor time and are likely to investigate everything from the Iran war to the Epstein files to DOGE cuts to alleged conflicts of interest on the part of the Trump family." DOGE refers to the Trump administration's controversial cost-cutting effort known as the Department of Government Efficiency.

In addition, Trump is likely to find it nearly impossible to get Senate confirmation for any picks for the Federal Reserve, the judiciary or other arms of the government, according to Cantrill. She said it "will be very difficult for President Trump to get anyone confirmed - controversial or not."

However, she said there "may be more compromise on certain issues, especially housing, if Democrats take both the House and the Senate, given that Democrats will need to show they can govern versus simply obstruct."

She argued that there would not be a huge distinction between Democrats controlling one chamber of Congress and both chambers, which she views as "the two most likely election scenarios." She said there would not be "vastly different outcomes" overall because Trump would continue to have veto power and because most legislation requires 60 votes in the Senate.

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-Victor Reklaitis