DES MOINES, Iowa (AP) — U.S. Sen. Joni Ernst, an Iraq War combat veteran and Iowa’s first woman elected to Congress, is expected to announce next month she will not seek reelection, leaving another vacancy in an Iowa seat that could have ripple effects down the ballot as Democrats look to the state for pickup opportunities.

As Senate Republicans work to maintain their majority in the chamber, Ernst is joining a wave of her peers making headaches for the party. Sen. Thom Tillis of North Carolina turned down a reelection bid after clashing with President Donald Trump.

Ernst plans to announce in September that she will opt out of the race for a third term, according to three people familiar with her plans who spoke Friday on the condition of anonymity to preview the announcement.

Ernst, a former Army National Guard member and a retired lieutenant colonel, was first elected to an open Senate seat in 2014. She served for several years in the No. 3 spot in the Senate GOP leadership and was considered a vice presidential contender for Trump’s first White House run.

Her decision comes after Iowa Gov. Kim Reynolds, the state’s first female governor, said she would not run for reelection. It prompted the state’s many Republican elected officials to consider the open opportunity to run for higher office, a process that may begin again with Ernst’s departure.