Denise Powell, a political organizer, won the Democratic primary election in a key Nebraska House district, according to The Associated Press.
She will face Brinker Harding, a Republican city councilman, in the general election, a pivotal contest in a battleground district that comes as Democrats try to recapture control of Congress this fall.
Representative Don Bacon, the Republican incumbent in the district and a frequent critic of President Trump, chose not to run for re-election, setting up a high-profile clash for an open seat in Omaha.
Ms. Powell narrowly triumphed in a competitive Democratic primary that centered on an unusual argument: that electing her chief rival, State Senator John Cavanaugh, could make it easier for Republicans to win the White House in 2028.
The argument stemmed from the way Nebraska allocates its electoral votes in presidential elections. Most states follow a winner-take-all approach, but Nebraska gives just two of its votes to the statewide winner, then gives one to the winner of each of its three congressional districts. In recent elections, the Omaha-area district has typically gone blue in presidential contests and awarded its electoral vote accordingly, even as the two other Nebraska congressional districts typically went to the Republican candidate.
That could make a difference in a close presidential contest.
State Republicans have tried to repeal the so-called blue dot system — named for the blue, liberal dot Omaha represents in a sea of Republican red — but Democrats in the State Legislature have been able to block that effort.
Mr. Cavanaugh’s opponents argued that if he won the House primary and left the State Senate, it would mean one fewer vote to keep the blue dot. Mr. Cavanaugh argued that the system was safe, and that Democrats were likely to be elected in other State Senate seats to compensate for his departure.
The argument may have been enough to help Ms. Powell to victory. A super PAC with ties to Republicans also spent against Mr. Cavanaugh.