Michael J. Fox is making his return to the midterm elections.

After cutting some memorable campaign commercials for now-Sens. Ben CardinBen CardinAide: Trump invited Philippine leader to WH Dem senator: Hold hearing on Russian interference in election Overnight Finance: Questions swirl around Trump's plan for his business | Treasury pick promises major tax cut | White House downplays Carrier deal MORE (D-Md.) and Claire McCaskillClaire McCaskillOvernight Defense: Funding bill would ease Trump Defense pick's confirmation | Obama delivers final security speech Congress wants hearing on Pentagon wasteful spending charges A Cabinet position for Petraeus; disciplinary actions for Broadwell after affair MORE (D-Mo.) four years ago, Fox is back in a new spot for Sen. Arlen Specter (D-Pa.).

"Arlen Specter is moving forward," Fox says. "He's won the battles to double funding for biomedical research, to find cures and to save lives.

"He's smart, tough and always moving forward."

Fox's 2006 midterm ads for Cardin and McCaskill drew plenty of attention, especially after Rush Limbaugh accused him of exaggerating the effects of his Parkinson's disease during the ads.

Specter faces Rep. Joe Sestak (D-Pa.) in the May 18 primary. If he wins there, polls show he would also face a tough match in November, with former Rep. Pat Toomey (R-Pa.) leading.