OKLAHOMA CITY (AP) — U.S. Rep. Kendra Horn easily dispatched her lone opponent Tuesday to capture the Democratic nomination in Oklahoma's 5th Congressional District, while Republicans were paring down a crowded field of congressional hopefuls looking to replace her.

In the race for Oklahoma’s U.S. Senate seat, incumbent U.S. Sen. Jim Inhofe defeated three GOP challengers and will face Democrat Abby Broyles, an attorney and former television reporter from Oklahoma City who also bested three primary challengers.

The real challenge for Horn, the only Democrat in Oklahoma's congressional delegation, comes in November. Nine Republicans are vying to replace her. The 44-year-old attorney pulled one of the nation’s biggest congressional upsets in 2018 when she won a seat that had been in Republican hands for four decades. Tuesday she defeated perennial candidate Tom Guild, a retired college professor from Edmond

Horn is considered one of the most vulnerable Democratic incumbents in the nation because she represents a district President Donald Trump won by nearly 14 points in 2016.

“I like her and think she's doing a great job," said Darla Ryan, 59, a Democrat who cast her ballot for Horn Tuesday at Life Church in Edmond, Oklahoma. “I voted for her last time, too."

Four of the GOP challengers have raised more than $500,000, including businesswoman Terry Neese, state Sen. Stephanie Bice, former state education superintendent Janet Barresi and businessman David Hill. The crowded field makes a primary runoff likely.

Horn has raised more than $3.3 million this cycle, the most of anyone in the state’s delegation.

While a record number of Oklahomans cast absentee ballots by mail this year, turnout was steady Tuesday at several polling places in the Oklahoma City metro area. At Life Church, most voters were wearing masks and maintaining social distancing in a line that stretched into the parking lot.

Savannah Steele, 19, a college student from Edmond who was voting for the first time, said the coronavirus pandemic made her uneasy.

“In Oklahoma, with (the number of reported cases) spiking, that was a concern, but with people staying six feet apart and wearing masks, it was fine," Steele said.

Two other Republican incumbents, U.S. Reps. Markwayne Mullin and Tom Cole, also won their primaries Tuesday. Republican U.S. Reps. Kevin Hern and Frank Lucas do not have primary opponents.

Also on the ballot Tuesday is a proposal to amend the Oklahoma Constitution to extend Medicaid health coverage to tens of thousands of low-income residents. Oklahoma is one of 14 states that have not expanded Medicaid — along with neighboring states Texas and Kansas—as part of the 2010 federal Affordable Care Act.