In truth, the only viable candidate is Romney, so if he doesn't win the primary, the GOP might as well throw in the towel because the rest of them suck.
Romney is pretty evenly matched with Obama right now in the polls. However, they are tied despite a sluggish economy. That says a lot about Obama. I think he is bound to only gain momentum from here on out. Afterall, the economy is actually improving a smidge. It just needs to remain consistent until 2012 (not very likely).
The short answer to the title of your thread is "no". The long answer is as follows:
1) Romney will almost certainly be the nominee. If you look at the primary schedule it favors Romney in a very big way. The early states gain momentum and campaign contributions go where the momentum is. Cain
could play a factor but his financial power is nowhere near what Romney can do. In addition to Cain's recent problems (which for the record I think are total bullshit) it really opens the door for Romney to hammer this down pretty quick...
provided there are no major surprises (which there always are).
2) Assuming Romney gets the GOP nod we need to look at the electoral map. No matter what Obama does he will score WA, OR, CA, MI, IL, MN, HI, MD, DC, DE, NJ, RI, CT, NY, MA, VT, and ME. That's 212 EVs out of the 270 needed to win that are locked in for Obama. He will
almost certainly get NM, and PA as well bringing him to 237.
Now Romney on the other hand has some locks as well. He will get AK, ID, MT, WY, UT, AZ, TX, OK, KS, NE, SD, ND, MO, AR, LA, MS, AL, GA, SC, TN, KY, WV, and IN. That's 191 EVs locked. He will
almost certainly score NC, NH (where he is
wildly popular), and FL. That brings him to 239.
Now you said before that Obama is tied with Romney and that's a good thing. No it's not. Historically, incumbents start with big leads, and Democrats also historically start with big leads and the Republican closes in as election day nears. Obama is a Democratic incumbent which means he should be getting a boost from both of these things. The problem is...he's not. Usually the GOP a year away from an election will gain 7-8 points by the time the election hits, and the incumbent usually has a good 5-7 point advantage to begin with. That means historically Obama needs to be 12-15 points ahead of Romney at this point in order to make it close.
When you consider that, and then look at the RCP averages in the remaining states you realize that OH, NV, and VA will most likely go to Romney and that gives him 276 already without even considering IA, WI, or CO (all of which I believe will ultimately go to Obama but are too close to call at this point and the polls in WI are showing a very strong lean to Romney as well).
So the short answer is "no" and the long answer is "oh
hell no"