It doesn't make sense to compare to election cycles pre-McGovern/Fraser reforms of the 1970s, since the nomination process was completely different back then. Since then, the GOP has almost always had a strong frontrunner going into the next presidential nomination cycle, up until 2008. In 2008 and 2012, the field was fairly splintered, with no overwhelming frontrunner in the mold of, say GW Bush in 2000.
I see 2016 as being another cycle in which there is no strong frontrunner on the GOP side, so it wouldn't necessarily take much to become the frontrunner. The boost of publicity associated with becoming Romney's running mate might be enough to do it, assuming the candidate in question does a decent job on the campaign trail.
Barring Romney's running mate becoming the frontrunner, I see Christie as being the most likely frontrunner for the 2016 GOP nomination (again, assuming that Obama wins reelection), so in my mind, this poll is equivalent to asking "Which of the potential Romney running mates could use their status as his running mate to eclipse Christie for 2016?" (Please, no fat jokes about "eclipsing Christie".
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Poll
