The runoff is being labeled as yet another symbolic battle between the mainstream Republicans and the conservative wing of the party. Byrne is considered the more establishment candidate in the race. He's consistently led in fundraising and polling throughout the primary and is running as a conservative bent on fighting federal government waste.
Earlier in September, Byrne's campaign released an ad promising to cut the Obama administration's wasteful spending on "robotic squirrels" and "a futuristic food menu for mars." He's also suggested support for getting rid of the Internal Revenue Service. Like most Republican candidates today, Byrne is also strongly critical of Obamacare.
Byrne's primary opponent is likely to hit him as a mainstream Republican who's only pretending to be a conservative (Byrne was a Democrat until 1997). Byrne has the support of prominent national Republicans like former Florida Gov. Jeb Bush (R), who endorsed Byrne when he ran in a bruising and unsuccessful campaign for governor of Alabama in 2010.
Young also has strong appeal among Tea Partiers and right-wing conservatives in the state. Tea partier Sharron Angle, who ran an unsuccessful campaign against Senate Majority Leader Harry Reid (D-NV) in his last time up for re-election, in an endorsement of Young.
Angle's endorsement captured much of the appeal Young offers his supporters. He's stood out as staunchly anti-gay rights, even in a crowded field of Republicans jockeying to be the truest conservative in every sense. Young aired a TV ad earlier in the campaign cycle arguing that he is "against homosexuals pretending like they're married. If you want to have homosexuals pretending like they're married, then go to the Democrat party."
Young was also able to push a number of the Republican special election candidates to formally pledge strong opposition to same-sex marriage. Young also claims support of Alabama Chief Justice Roy Moore, an influential figure in the state who refused an order by a federal judge to remove the Ten Commandments from the Alabama Supreme Court building. Young also previously ran for Bonner's seat in 2012.
Because the Republican primary was so wide open, national figures seeking to score a few political points of their own by picking the right Republican candidate in the special election, haven't all coalesced around either Young or Byrne. Former presidential candidate Rick Santorum, for example, endorsed a losing candidate in the primary, conservative pundit Quin Hillyer.
Supporters of Hillyer and the other Republican primary candidates, both big name endorsers and just regular voters, are likely to eventually throw their support behind either Byrne or Young which could be the deciding factor in who gets the nomination -- and realistically wins the seat as a Democratic victory is unlikely. After it was clear he was out of the race, Hillyer quickly endorsed Byrne.
In response, Byrne said that Hillyer's endorsement "is one of the best things that happened to us tonight."