The 2016 demise of Marco Rubio has been obvious for a while, but it is nevertheless a very big event. He was the Republican Party's choice. He lost.
Starting last fall, I said he would be the most likely winner. I continued saying that through the early primaries and caucuses. In fact, he seemed on track to win up until his disappointing Super Tuesday on March 1, and even in the days after that I thought he was in fairly good shape -- that is, right up until his support collapsed the weekend after Super Tuesday.
Since I have been dead wrong about Rubio, I can't turn around immediately and tell you why he lost. It's something all of us who study presidential nominations are going to need to study, and it's going to take some time, especially for those who believe that strong parties made up of formal organizations and informal networks control their presidential nominations.
Is this year a fluke? A sign that the system has changed? Frankly, I don't know right now.
But I can run through some reasonable explanations of what happened with Rubio.