OKLAHOMA CITY (AP) — A question on whether to expand Medicaid in Oklahoma and a crowded Republican field vying to challenge the state's lone congressional Democrat are drawing the most attention ahead of Tuesday's primary election.

State Question 802 would amend the Oklahoma Constitution to expand Medicaid health insurance to those earning up to 138% of the federal poverty level, which is about $17,200 for an individual or $35,500 for a family of four.

Oklahoma is one of 14 states — along with neighboring Texas and Kansas — that have not expanded Medicaid under the 2010 federal Affordable Care Act, mostly because Oklahoma's Republican governors and Legislature have resisted. Residents instead petitioned to put the measure on the ballot.

According to the nonpartisan Kaiser Family Foundation, states that have expanded Medicaid through a ballot measure include Idaho, Maine, Nebraska and Utah. A vote in Missouri is scheduled for Aug. 4.

Oklahoma's proposal has endorsements from chambers of commerce, medical groups, the Oklahoma Education Association and the Oklahoma Conference of Churches, along with most Democrats in the Legislature.

But Republican Gov. Kevin Stitt has been a fierce critic, saying the proposal could lead to tax hikes or budget cuts to other programs, including education.

“I’m going to be voting no on SQ 802. This is going to cost our state $200 million," Stitt said during an event this week with Americans for Prosperity. “We have a billion-dollar shortfall next year.”

The Oklahoma Health Care Authority has projected that about 215,000 residents would qualify for a Medicaid expansion, for a total annual cost of about $1.3 billion. The estimated state share would be about $164 million.

If the proposal passes, the Legislature is expected to increase a fee that hospitals pay from 2.5% to 4%, which would generate about $134 million annually. Stitt vetoed such a measure this year.

In another closely watched contest, Republicans in Oklahoma City's 5th Congressional District will pare down the field of nine GOP candidates vying to challenge U.S. Rep. Kendra Horn. Many pundits say the first-term incumbent is one of the most vulnerable in the nation because she represents a district President Donald Trump won by nearly 14 points in 2016.

“Republicans clearly see OK-5 as one of their best chances to ‘flip' a House seat, and they’re correct to see it that way," said Matthew Motta, a political science professor at Oklahoma State University. “The race has attracted several fairly well-financed challengers. And, because President Trump won the district by more than 13% in 2016, most non-partisan election analysts classify the race as a toss-up."

Four of the GOP challengers have raised more than $500,000, including businesswoman Terry Neese, state Sen. Stephanie Bice, former State 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 any of the state's delegation. She faces perennial candidate Tom Guild, a retired college professor from Edmond, on Tuesday.

Republican U.S. Sen. Jim Inhofe and U.S. Reps. Markwayne Mullin and Tom Cole all are heavy favorites in their GOP primaries Tuesday.