Republican primary voters casting ballots for an open U.S. Senate seat in Arizona are unlikely to see a televised debate despite calls from two of the three candidates.

Rep. Martha McSally, former state Sen. Kelli Ward and former Maricopa County Sheriff Joe Arpaio are vying for the Republican nomination to fill the seat of retiring Sen. Jeff Flake.

Ward has been calling for a debate for months. Arpaio posted a Twitter letter Wednesday challenging his opponents to a televised debate. But McSally says with the primary less than two weeks away, she's engaging directly with voters and debunking attacks from her opponents.

"We've got 13 days, we're sprinting to the finish," she said. "We're pretty sure primary voters know where the other opponents stand on a lot of issues, so we're engaging with primary voters and building our momentum and enthusiasm so we can shore up this nomination."

McSally also pointed to a closed-door forum that she and Ward attended at The Arizona Republic. She said a transcript is available to those who wish to see it.

McSally spoke to the press in Phoenix after a campaign event announcing the launch of her Women's Coalition. Standing beside former Arizona Gov. Jan Brewer and businesswoman Lynn Londen, McSally told supporters about the challenges she faced on her path to become the first female fighter pilot to fly in combat.

For national Democrats, the open seat in Arizona is a key pickup in their quest to take control of the U.S. Senate. On the Democratic side, Rep. Kyrsten Sinema and activist Deedra Abboud haven't had a televised debate either — though Abboud has said she's open to one.

The primary is Aug. 28, with around 400,000 early ballots already cast, according to figures from the Arizona Secretary of State.

McSally, who has represented a southern Arizona district in the House of Representatives, has picked up support from many establishment Republicans. Ward, who previously ran in a primary against Sen. John McCain, is popular among many of the state's most conservative voters. Arpaio has statewide name recognition from his longtime tenure as sheriff. All three candidates have been playing up their connections to President Donald Trump, though he has not made a formal endorsement in the race.

In calling for a televised debate, Arpaio said, "voters have a right to hear from us, to see us interact with each other on stage and to have an open discussion" about who can best represent them.

Ward's campaign says she's been calling for debates since January. Last week, she sent a letter to Arizona Republican Party Chairman Jonathan Lines saying that she will only sign the party's Unity Pledge — a vow to back GOP nominees in the general election— if it's on a debate stage.

"There is no unity when candidates refuse to debate, and I refuse to pretend otherwise," Ward said in a statement. "Arizona deserves better and I sincerely hope Chairman Lines will join me in advocating for taking every action possible to educate voters on their choices for U.S. Senator prior to the election."