It's not surprising that people are paying more attention to the race than they were in January, of course, since now there's voting and stuff. Nor will it likely surprise you to learn that the people finding themselves less enthusiastic about the whole thing are mostly Republicans.
"Republicans' enthusiasm about voting since January has slipped more than Democrats'," Gallup's Frank Newport writes, "leaving an equal 46% of both partisan groups extremely or very enthusiastic at this point. The overall average of 43% is pulled down by the very low enthusiasm among independents who do not identify with or lean toward either party." In January, Republicans were 5 percentage points more enthusiastic than Democrats.
Gallup also found that Republicans were losing confidence in the electoral process itself. In January, nearly half thought the system was working (versus about a third of Democrats). Now, Republicans are less confident in the process than those on the other side of the political spectrum.
On the enthusiasm thing, it's worth noting that people were much less excited about voting as the primaries ground on in 2012, too. That year, the amount of enthusiasm about voting was even lower than it is now, perhaps as a function of a grinding, hard-fought slog leading up to the Republican nomination. But by the general election, enthusiasm rebounded.
So perhaps this is just a lull. Perhaps, as the weeks grind on and the parties either narrow in on a nominee or explode like fireworks in the skies over Cleveland and Philadelphia, voters will start getting more into it again.
If this year has taught us any lesson at all, it's that anything can happen.