Is Cain able?

So here is one test to see whether Mr. Cain is a long shot — or a big shot. Will he begin to receive more endorsements from Republican elected officials, and key party officials in states like Iowa and New Hampshire, in the coming days?

Mr. Cain has begun to get more attention from Republican opinion-makers: The Wall Street Journal had an editorial that was favorably disposed toward him on Wednesday, for instance. Writers and talking heads, however, can change their opinion on a moment’s notice, and can usually count on their readers and viewers having short memories. A formal endorsement is more of a commitment, and Mr. Cain has seen very few of those so far.

The other litmus test is Iowa, where there have been few credible polls conducted in recent weeks. But the former leader in Iowa, Mrs. Bachmann, has since seen her numbers slump badly in national polls. Tim Pawlenty has dropped out of the running, meanwhile, while Mr. Romney has yet to fully commit to the state for fear of raising expectations.

That would seem to open the door for Mr. Cain.