"When Jon Tester says Denny Rehberg doesn't care about cancer victims, he's playing politics with a deadly disease," Rehberg's mom says in the ad. "For 30 years Denny has helped me battle cancer — from breast cancer now to thyroid cancer — he's been with me because Denny has a good heart and understands what it does to everyone it touches. I know, because Denny's my son."
The two are locked in a tight — and increasingly personal — race that could determine control of the Senate.
The Hill rates the race a "toss-up."