In the ad, Judy Susser tells the story of her son, Adam, who is blind, quadriplegic and has cerebral palsy, while clips of the family play. She says that embryonic stem cell research is his "best chance" to be able to walk and see. According to the ad, the family met West at a charity event.

"When we asked Allen West if he'd support this research, he just turned his back on all of us, on Adam, and just walked away without saying a word," she says.

"If Allen West could turn his back on Adam, what will he do to you?" she asks at the end of the ad.

It's the second attack from House Majority PAC on West's opposition to stem cell research. Their first ad targeting him on the issue features three actors sharing hypothetical stories of how stem cell research could help them, and questioning West's refusal to support it. A version of that ad has run in two other districts, against Rep. Dan Lungren in California and Mike Coffman in Colorado.

But West's campaign pushed back against the ad, calling it false and pointing out that the Sussers have contributed thousands to Democratic candidates in Florida, including West's 2010 opponent.

“Congressman West has great compassion for the Susser family, for their son and the disabilities he faces. However, the Susser’s allegations that they were ignored by Congressman West simply aren’t true. In fact Congressman West corresponded with the Susser’s and even invited them to attend two town hall meetings," said Tim Edson, West's campaign manager, in a statement.

"It is truly despicable that Patrick Murphy and his allies at House Majority PAC would exploit a disabled child for their own political gain,” he added. 

West faces a strong challenge from Democrat Patrick Murphy, and polls of the race have been all over the map, indicating the two are likely running close. It's a race characterized by sharp attacks from both sides, as West used Murphy's mugshot in one ad, and Murphy shot back by highlighting West's resignation from the military after being charged under the Uniform Code of Military Justice for misconduct.

Watch the ad: