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

After cutting some memorable campaign commercials for now-Sens. Ben CardinBen CardinDem senators urged Obama to take action on Russia before election Overnight Cybersecurity: Trump tweetstorm on Russia probe | White House reportedly pushing to weaken sanctions bill | Podesta to testify before House Intel Senate expected to pass Russia sanctions bill for a second time MORE (D-Md.) and Claire McCaskillClaire McCaskillSenators question need for HHS cyber office Overnight Cybersecurity: Obama DHS chief defends Russian hack response | Trump huddles on grid security | Lawmakers warned about cyber threat to election systems We must protect our most vulnerable from financial fraudsters 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.