It's never too soon to start paying attention to the elections that are just around the corner. There are already politicians jockeying for position at the top of the Republican ticket. There are actually many different prospects at this point since it is possible that anyone can catch the public's imagination. And it is the ability to catch the public's imagination that is, arguably, the most important thing for a politician at this point in the race.
One of the things necessary is to be able to convince the money men of the party that they are able to deliver the votes. It is only after they demonstrate that they can deliver the votes that they will be rewarded with the contributions that will help them run their campaigns.
So yes, it is essentially a popularity contest at this point.
The first person on my list is Marco Rubio (see his profile on Wikipedia). He was selected to give the Republicans' response to the State of the Union address by President Obama. While we may never know the exact reasons why he was chosen, he is being tested as the new face of the Republican party. Nate Silver at 538 (New York Times) has even written a piece about him judging some of his initial positions.
So how does he shape up? Pretty well at this point. He has descent name recognition for this stage of the game. He is also Hispanic with an immigration plan. Since the thinking of the Republican party after the last election was that they lost, at least partially, because of a lack of Latinos willing to vote for them; putting forward a Latino with a plan for fixing what is assumed to be the Latinos' biggest problem seems to be a reasonable strategy.
Marco Rubio will be one of the politicians I watch to see whether he can catch a wave of public support or whether he is more of a flash in the pan on the way to a different nominee.