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