Two Democratic super-PACs are going back on the air with buys in Montana and Missouri, a Republican ad-buy tracker told The Hill.

Patriot Majority will spend $200,000 on broadcast ads in Montana beginning on Friday and running through June 5, while Majority PAC will spend $160,000 on ads in St. Louis and Kansas City beginning Friday and running through May 31.

The groups did not immediately respond to requests for comment on what types of ads they will run.

The states are expected to have two of the closest Senate races in the country, with Sens. Claire McCaskill (D-Mo.) and Jon Tester (D-Mont.) locked in tough reelection fights. They already been deluged with outside group attacks — Montana alone has seen $3 million in outside group spending.