With the candidate himself
"As a good rule of thumb, until things go past allegation to fact I just try to leave them alone," Texas Gov. Rick Perry said Tuesday when asked about the story.
Former Massachusetts Gov. Mitt Romney's campaign has not responded to repeated requests from CBS News for comment on the allegations.
Former House Speaker Newt Gingrich, who is set to engage in a "modified Lincoln-Douglas debate" with Cain Saturday, has also declined to weigh in. Ron Paul and Jon Huntsman have also steered clear of the story; Paul said Wednesday that "I hate seeing this come about when you don't know who's making the allegations and what the charges are."
The candidate who has come closest to directly criticizing Cain directly over the story is Rick Santorum. Asked about the situation Wednesday morning, Santorum said, "I don't have any comment, I think like everybody else I just wait and see how this all plays out," adding that "we're still in the middle of the story."
But on Monday, Santorum responded to CBS News and National Journal's Rodney Hawkins' question about the story this way: "My feeling is that you're going through a political process, one of things you want to make sure is that you have candidates that have been through it."
"Whether it is on public policy issues and being able to deal [with] questions on complex public policy issues to things that are in the person's background, you want someone who is running for president of the United States who can stand up to that and has been through that process before," he added.
And on Tuesday at a National Journal forum, Santorum's campaign manager criticized Cain for his evolving story about what took place and said Cain's campaign needs to be "forthcoming so that you are vetted."
Rep. Michele Bachmann, meanwhile, has not directly referenced the story. But on Tuesday, she told supporters that "[t]his is the year when we can't have any surprises with our candidate."
"We have to have a candidate that we can know when we put them into office we can trust them with their record of what they have done and who they are," she said. "I have that record, and I have stood strong, and I have stood on those issues."
There has been speculation that one of Cain's rivals leaked the story in an effort to slow Cain's momentum, though no evidence has surfaced to support such claims.