If ANY U.S. president were to open trade with Cuba under Castro, it would have to be a Republican. Remember the ancient Vulcan Proverb: "Only Nixon could go to China"?
Same is true with Cuba-a democrat would be crucified for trying to open trade with Cuba, and would be called "soft on communism". A Republican, however, from the party of McCarthy and Nixon, could get away with it as being an "open-minded" statesman. It's just the way it works sometime.
The embargo against Cuba is outdated and counter-productive anymore, despite Cuba's less-than-stellar human rights record. If we can trade with China, why not Cuba? Well, I can answer that-Cuba doesn't have a billion and half consumers.