First-time political candidate David Perdue won a surprise victory over favored Rep. Jack Kingston in the Republican runoff for the US Senate nomination in Georgia. Kingston, who had the backing of the US Chamber of Commerce as well as conservatives such as my Salem colleague Erick Erickson, had been leading in almost every poll as the runoff approached. In the end, Perdue’s outsider message may have won the day:

Businessman David Perdue stunned Georgia’s Republican political establishment Tuesday by capturing the party’s U.S. Senate nomination in his first run for office.

The former CEO of Reebok and Dollar General toppled 11-term Rep. Jack Kingston by a narrow margin, setting up a battle of political newcomers with famous kin in the fall. Perdue’s cousin, Sonny, was a two-term governor and Nunn’s father, Sam, was a four-term U.S. Senator.

In addition to his famous last name and lingering political network from his cousin, Perdue deployed $3 million of his own money to back his bid. Still, he was outspent by Kingston and allied Super PACs – including the deep pocketed U.S. Chamber of Commerce.

That leaves the Senate race in Georgia to two political neophytes — Perdue and Michelle Nunn, who has also never run for office until now. Both come from political families, however.  Nunn’s father Sam spent four terms in the Senate before retiring in 1996 as a blue-dog Democrat who voted in favor of tort reform and in support of the death penalty and balanced budgets. Nunn’s challenge will be to convince Georgia voters that she’s a chip off the old block while still representing the outsider, anti-establishment perspective.

Perdue’s win makes that a little more difficult, Politico’s James Hohmann points out:

The general election is likely to be a costly battle between two candidates running as “outsiders,” despite their politically powerful families. Democratic nominee Michelle Nunn’s father, Sam Nunn, represented Georgia in the Senate for 24 years. Perdue’s first cousin, Sonny Perdue, was the state’s first Republican governor elected since Reconstruction, serving two terms from 2003 to 2011.

With Kingston’s defeat, Nunn has lost her chance to run against Washington and the national debt. She is expected, instead, to contrast her background as a nonprofit executive against Perdue’s tenure as a CEO at companies like Reebok and Dollar General.

Georgia is the Democrats’ best chance to pick up a Republican-held seat this fall, which ensures it will be one of the most closely watched races on the map.

Democrats might have hoped for a GOP split such as that seen in Mississippi after a close primary and runoff. If so, they’re doubly disappointed as Kingston wasted no time in endorsing his former opponent:

Kingston immediately pledged his support in a concession call to Perdue and told him “once we combine our two camps we will absolutely be unstoppable.”

Erick blames the Chamber of Commerce endorsement for the narrow loss:

In the last two weeks, David Perdue made hay out of walking out of his meeting with the Chamber. He claimed the Chamber wanted him to vote with them 100% of the time. He would not.

That message resonated. Kingston was the career politician in the pocket of the Chamber and would pass amnesty.

Not now. He lost. And he did so largely because David Perdue made Kingston own his Chamber of Commerce endorsement.

Erick’s a lot closer to the race than I am, and the narrowness of the runoff makes this a very plausible analysis. It might be simpler than this, though. Kingston’s been in Washington for 22 years, and with or without the Chamber of Commerce endorsement, that’s baggage in the last few cycles. Georgia voters may just have wanted a reasonable alternative to a career politician, and Perdue managed to make that case for himself in the course of the primary and runoff. Don’t discount the power of populism in this cycle — and it might be fortunate for the national GOP that they defused that argument in Georgia, assuming Perdue doesn’t blow the general election.