The short answer is yes but I'm wondering if he's having what I call a "Howard Dean" moment. The former governor of Vermont came out of nowhere in late 2003 seizing on the anti-Iraq fervor in the Democratic party and found himself in first place just before the Iowa caucus. In fact, many felt he was a prohibitive favorite to win the nomination but at the last minute a letter was released (nobody knows who although it was probably Bill Clinton) showing Dean's support for Clinton's unilateral military strikes in Yugoslavia in 1998. This undercut Dean's claim as an antiwar liberal, and, after his disastrous speech the night he lost the Iowa caucus sunk him and allowed John Kerry to seize the nomination.
Right now it certainly seems that Cain is the "stop Romney" candidate. He's conservative fiscally and socially and seems very likeable to most that seem he him in stump speeches. He's gotten his biggest lift from the debates; he seems comfortable and plain spoken. He's got a great life story and he's unapologetic for his political positions. His "9-9-9" plan seems to resonate with a lot of voters but I think this will be his Achilles Heel. If he wins the nomination the Democrats will hit him over and over again with the idea of a 9% sales tax as a "regressive tax" on the poor. That's political dynamite and will be hard to handle.
Having said all that, two months is basically a geological ice age and so much can happen. A month ago the conventional wisdom on the GOP side was that Perry would be the "stop Romney" candidate. Perry has since faded into obscurity, chewed up by his own incomprehensible answers in the debates while Herman Cain shined. Conservative GOP voters will probably have to decide in the next two months whether or not they'll take the more moderate Romney or whether they'll gamble on a untested conservative like Herman Cain. Right now my money is on Cain. If anything, it would be very funny to watch the Left attack him, an African American who, unlike the current President, actually was the victim of racial discrimination who rose from obscurity to be a successful businessman.