Editorial note: Dr. Sanjay Gupta joins AC360 tonight at 8 and 10 p.m. ET. Anderson will talk to him about his stunning investigation into the tragic injuries suffered by football players from hits to the head. Watch their discussion and see "Big Hits, Broken Dreams' on Sunday, January 29 at 8 p.m. and 11 p.m. ET.

One day late in the summer of 2010, I was sitting in my backyard with my oldest daughter. We had just finished cutting the lawn when my neighbor and his oldest son stopped by.

His son, a football player at one of the powerhouse local high schools, had grown nearly an inch over the summer and weighed more than 200 pounds. He was already in practice for the upcoming season. He asked if I had time to speak to a friend of his who also played football and had suffered a concussion the previous season.

They were asking me in my capacity as a neurosurgeon, but also in desperation, as this young man was still having tremendous difficulty nearly a year after his injury.

Most of the patients I see in the hospital visit me at the time of their injury, and I hardly ever get to see the longer term impact of a severe concussion on an otherwise healthy young person. What he shared with me was stunning, and also formed the basis of the year long project, "Big Hits, Broken Dreams."

This young, physically robust, handsome man couldn’t remember the details of the hit in a mid-season practice that led to his concussion, but he was able to describe in awful detail how much his life had changed since.

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If you’re looking for a haven of sanity and logic, Florida wouldn’t necessarily be your first stop. But Republicans have got no choice: Tuesday’s vote may be the party’s last shot at imposing order on the spiraling chaos of the primary season. So far, signs aren’t promising.

The GOP race looks like a dead heat in the CNN Florida poll released yesterday, with Romney at 36% and Gingrich at 34%. A 25 point Romney lead in our last poll basically evaporated in just two weeks’ time.

But is the race really neck-and-neck? Maybe. Probably. But the truth is: right now, nobody really knows. We’re seeing significant day-to-day swings in the numbers, with both men trading momentum over the course of our three-day poll: Gingrich holding an undeniable advantage one day, Romney holding a significant edge the next. We’re now in uncharted territory - this late in the season, this is not how Republican presidential campaigns work.

What’s driving the numbers? The evidence isn’t all that clear-cut. But here’s one clue: unfavorable ratings for both men are rising by double-digit margins in virtually every poll. In other words, as the campaign grows bloodier by the day, it’s as though Florida Republicans wake up each morning and think to themselves: Who do I like less today?

FULL POST

With 50 winner-take-all delegates, the Florida primary could be a game-changer in the race for the Republican presidential nomination. That makes tonight’s debate - hosted by CNN, the Republican Party of Florida and the Hispanic Leadership Network - crucial to the candidates’ fight to the top. It’s one last opportunity for a face-to-face showdown before Tuesday’s vote.

Tune in for the debate at 8 p.m. ET on CNN, and don’t miss Anderson’s post-debate show for the best recap and analysis. Also, don’t forget to send your questions for the candidates by using #CNNDebate on Twitter.

Two members of congress, both Republicans, say Gingrich lobbied them on behalf of Freddie Mac. Anderson Cooper reports.