Based on the last two major Senate races for that seat (Rubio and Mel Martinez), here's how it will likely unfold:
Atwater won't get in. Some drab "establishment politician" (Porter Goss type) will seek the job, and Lopez-Cantera will run to his right and scream "TEA PARTY!!!" at the top of his lungs. The FL Tea Party groups will then immediately fall over themselves to endorse him, and accuse anyone who DOESN'T blindly "get behind" Lopez-Cantera of being part of the "GOPE". Lopez-Cantera will insist over and over on the campaign trail that he "disagrees" with Rubio about amnesty and believes in "border security first". He will release a campaign statement saying "I do not favor a path to citizenship for people who entered the United States unlawfully. We should not reward people who broke the law". A bunch of FL freepers will claim they know Lopez-Cantera and that is as an "outstanding, pro-life, traditional family values, rock solid conservative guy" Anyone who asks for evidence that Lopez-Cantera has consistently opposed amnesty and has a track record of doing so will be accused of "racism" against a Hispanic candidate.
"Tea Party" Lopez-Cantera will beat the "GOPE" candidate, and then promptly endorse amnesty about 3 weeks after being sworn in as U.S. Senator.
Unnnnghhh.