House Majority PAC, a Democratic-aligned group, is going on the air in California’s 10th district against freshman Republican Rep. Jeff Denham.

The group is launching a Medicare-themed television ad that targets “Denham’s plan” for Medicare and states that his Democratic opponent, astronaut Jose Hernandez, would strengthen the program. The ad hits the Sacramento airwaves Saturday and will run for a week and a half behind a six-figure independent expenditure.

The ad comes a few days after the Democratic Congressional Campaign Committee released an internal automated poll that found Hernandez taking a 2-point lead, within the poll’s 5-point margin of error. That survey of 382 likely voters was conducted on Sept. 10, on the heels of Hernandez’s first flight of TV ads.

A poll conducted by Democracy for America last month had found Denham ahead by 9 points.