Donald Trump Should Be Worried About Marco Rubio, Not Ted Cruz

As the beginning of this week, most of the nation assumed Donald Trump would win Iowa's Republican caucuses. Trump certainly believed he would. As he remarked just a couple of days prior to the caucuses,

The folks in Iowa have been amazing to me. They've been amazing. I'm even leading in all of the polls in Iowa now. Some big ones are coming out I guess — but they don't even matter anymore, to be honest, because we're so close to the end, what difference does it make.

Of course, Trump didn't win the Iowa caucuses. Ted Cruz did. And Trump isn't happy. In fact, he has accused Cruz of stealing the election and is calling for Cruz's win to be nullified or that a new Iowa vote to take place. Cruz's campaign, evidently, sent an email that told caucus-goers that candidate Ben Carson was dropping out of the race, a claim, of course, that wasn't true (at least not yet -- it will happen eventually, however). There is little empirical evidence that this had much of an effect on the final results, however, since in the end Carson won 9.3% of the vote, which was a little bit lower than the final Des Moines Register poll (10.0%) and little bit higher than FiveThirtyEight's predicted result (8.7%).

More importantly (at least for Don Trump supporters), Trump needs to stop focusing on Ted Cruz and pay more attention to his real competitor, Marco Rubio. Rubio may have only finished third in Iowa, but as I've noted in previous posts ("Don't Write Marco Rubio Off Just Yet" "Rational Actors, Irrational Outcomes, and the GOP Nomination"), Rubio is positioned to attract increasingly more votes as establishment candidates, such as Jeb! Bush, Chris Christie, John Katich, drop out of the race. Rubio doesn't even have to win the New Hampshire primary. All he has to do is finish a strong second, which should force at least two of the three establishment candidates to drop out (or, rather, "suspend their campaigns").

There is evidence that mainstream Republicans are beginning to see Rubio as the candidate who has the best chance of winning in November. Since the Iowa caucuses, Rubio has received several key endorsements, including one from South Carolina Senator Tim Scott, the only African-American Republican member in the U.S. Senate, and Rubio is now the new leader of FiveThirtyEight's "Endorsement Primary" ("Marco Rubio Is Now Winning The Race For Endorsements"). Endorsements are a surprisingly accurate predictor of who eventually win the Republican and Democratic nomination :

There has been a lot of debate this presidential campaign about how much influence party elites have on the nominating process, but endorsements have historically been among the best signs of which candidates will succeed in primaries. And although four more endorsements and a slight lead in points do not make Rubio a lock as the choice of Republican elected officials, this bump is a sign that members of Congress could be starting to see him as the most acceptable option for the nomination. (Rubio has yet to receive an endorsement from a sitting governor.) Some politicians had put early support behind Jeb Bush — he had led our list since August — but since January the only new endorsement he has received was from former presidential candidate Sen. Lindsey Graham.

It will be interesting to see how things shake out in New Hampshire. According to the polls, Trump holds a YUGE lead, somewhere around 20% over Cruz and Rubio. There is still a week to go, however, and I think it's unlikely that Trump will win by that much. A win of 5-10% is more likely. Who knows, he may not win at all.