Agriculture Secretary Tom VilsackThomas J. VilsackUSDA: Farm-to-school programs help schools serve healthier meals OVERNIGHT MONEY: House poised to pass debt-ceiling bill MORE will not run for retiring Sen. Tom HarkinTom HarkinGrassley challenger no stranger to defying odds Clinton ally stands between Sanders and chairmanship dream Do candidates care about our health or just how much it costs? MORE's (D-Iowa) seat in 2014, easing one potential obstacle in Rep. Bruce BraleyBruce BraleyCriminal sentencing bill tests McConnell-Grassley relationship Trump's VP list shrinks Vernon wins Iowa House Dem primary MORE's (D) pursuit of the nomination.
“He will not seek the open seat" Vilsack aide Matt Paul told The Des Moines Register.
But Paul said Vilsack will focus on his job as Agriculture secretary, instead of making a run for Senate.
Braley is currently the only announced contender for the seat on the Democratic side, and Vilsack's decision not to run makes him the front-runner.
Republicans will see a fierce primary fight, likely between Reps. Steve King and Tom Latham, though neither has officially launched a campaign.