Fewer congressional contests are expected to be competitive this fall, compared with past election cycles, and experts say the extraordinary mid-decade redistricting efforts initiated by President Trump are largely to blame.

Fewer competitive seats means the overwhelming majority — more than 90% — of congressional races will pretty much be decided during primary elections, which see far fewer voters participate than general elections.

"Right now, we only rate 18 out of 435 races as toss ups, which means that less than 5% of Americans will truly be deciding who's in control of the House," David Wasserman, senior elections analyst for the Cook Political Report, told NPR.

This disparity in the voting power of Americans in congressional races has been a worsening problem for several election cycles.

Unite America Institute, which tracks what it refers to as the "primary problem" and advocates for election reforms, calculated that in 2024, just 7% voters elected 87% of U.S. House races.

Voters have self-sorted themselves geographically, and technology in recent years has allowed lawmakers to more effectively carve up congressional districts that give one party an advantage over another.

Nick Troiano, executive director of Unite America, said the mid-decade redistricting prompted by Trump last year has further reduced the number of competitive seats. His organization says 32 states currently don't have a single competitive congressional race.

"The primary problem is bad and getting worse," he told NPR. "We are about to enter a midterm election season that will be the least competitive of our lifetimes, which means that we will have, no matter who wins in November, the least accountable Congress of our lifetime."

Last year, Trump asked Texas lawmakers to redraw the state's congressional map to create five more seats that could favor Republicans in 2026. Democratic leaders in California responded, putting forward a successful ballot measure to circumvent the state's independent redistricting commission and create five more favorable seats for Democrats.

Lawmakers in other states, including North Carolina and Missouri, crafted new maps as well, and Florida and Virginia are among the states that may join them.

But so far, Wasserman said the redrawing of congressional boundaries ahead of this year's elections hasn't led to any "pronounced advantage" for either Republicans or Democrats.

"Instead, what it's done is it's eviscerated the competitive range of districts in which Americans have a real say over who controls Congress in November," he said.

Wasserman explained that even if one were to include races that Cook rates as "leaning" toward one party or another, that would only be 36 seats.

"That's still less than 10% of the House," he said. "By comparison, at this point in Trump's first term, we had 48 races that were competitive between the two parties."

Wasserman said new district lines in California and Texas are driving most of this.

"Whereas we used to have a robust number of Republicans from California and Democrats from Texas and Florida, today blue states' delegations are becoming bluer, red states' delegations are becoming redder," he said. "And there are fewer opportunities for bipartisan dialogue."

Primary voters tend to be more ideologically extreme than the general public

Troiano said there are some serious democratic issues raised by the fact that so few voters will have so much power to decide what party will control Congress.

For one, he says, primary voters are not representative of the broader American electorate. According to an analysis from his group, primary voters tend to be older, whiter, wealthier, more educated and more ideologically extreme than the general public.

"And so when you look at an old, white, wealthy Congress that is ideologically polarizing, can't get anything done, they reflect exactly who sent them there," Troiano said.

There have been some efforts in recent years to open up primaries to independent voters — which is the fastest-growing part of the U.S. electorate. New Mexico, for instance, now allows non-affiliated and independent voters to participate in party primaries. However, Louisiana and West Virginia recently went the other way, restricting some primaries to just registered party members. Currently, 17 states have either completely closed or partially closed primaries.

And in 2024, there were several ballot measures before voters in states like Arizona, Colorado, Nevada and Oregon that would have created nonpartisan primaries. But those statewide efforts failed across the board.

Unite America advocates for nonpartisan primaries or the inclusion of independent voters in party primaries for a slew of reasons, but one of their biggest arguments is that they allow more voters to take part in the most determinative elections.

And that's especially important, Troiano said, as more states whittle down the number of competitive seats.

"So if you think dysfunction and division is bad right now in Washington," he said, "it's going to get worse in the next congressional session because of the lack of competition in this year's elections."