DES MOINES, Iowa (AP) — Rural southwest Iowa state Sen. Joni Ernst has emerged as a front-runner in what once was a jumbled field of Republicans hoping to succeed retiring Democratic U.S. Sen. Tom Harkin. Ernst has managed to bring together warring factions of the state and national GOP before the primary. She has aired ads featuring her firing a handgun at an indoor shooting range and talking about her childhood experience castrating hogs.

Today’s (Tuesday’s) primary is significant because Iowa, a traditional swing state, is expected to play a key role in the race for U.S. Senate control this fall. Republicans need six seats to gain a majority. Neither party will have the power of incumbency in the race. The GOP views Democratic U.S. Rep. Bruce Braley, the assured nominee, as vulnerable.