The difference for races in the coming weeks may come between open and closed primaries.
An open primary means anyone can go into and vote in any party primary. A closed party means only registered party voters can vote in that party's primary.
So far establishment party voters in closed primaries favor Senator Ted Cruz. Open primaries are going to Donald Trump. The Florida primary in two weeks is closed, which might favor Senator Marco Rubio. But polling shows Trump with a big lead there already.
South Plains College professor Drew Landry explains the quandary facing the Florida Senator.
"Senator Rubio has to make up his mind as to what he wants to do," Landry said. "If that will be his last stand in trying to say 'I can win'. And that might be the place where he really makes that statement."
Another example is Oklahoma. It was a closed primary and it went for Cruz.
