In the most recent Gallup poll American voters are 27% Republican, 27% Democrat, and 43% Independent. A record high for Independents. When asked which way they "leaned" Independents were split pretty much evenly bringing the total to 45% Republican and 44% Democratic.
That leaves 11% of the voters up for grabs.
source Even Republicans are not excited about their candidates. Once they've made a decision which one gets to run in the general election it's hard to imagine that American voters at large are going to be particularly thrilled with the idea of voting for a Trump/Carson/Bush/Cruz/Rubio.
The Democratic field is far more mainstream and is addressing the issues that, poll after poll, say Americans are more interested in than the divisive social issues predominating the Republican discussion.
If Webb has the financial backing to continue his run as an indepent it's far more likely he'd do more damage to Republicans than Democrats. I don't see him as a game changer in any event though.
