Trump will head to New Hampshire the next day.
The former New York governor said he can "overcome the odds" in the White House race.
Cain pointed to an article that argues Santorum will have less traction than in 2012.
Donors can win a signed photo of father and son.
Scott Wong 05/28/15 12:22 PM EDT
The former Maryland governor is expected to launch a presidential campaign this week.
Jones, who sued Bill Clinton for sexual harassment, said Hillary should not be running.
Mario Trujillo 05/28/15 11:07 AM EDT
He wants to require states to offer online voter registration.
The decision comes ahead of the South Carolina Republican's 60th birthday.
Richard Trumka said support of the TPP would cost Clinton the enthusiasm of organized labor.