An unknown Baptist, Korean-American businessman from Augusta, Ga., delivered a speech July 19 to a regional conference of the National Federation of Republican Women. Sources say he shelled out $5,000 to serve as a “presenting sponsor” of the Atlanta event for 300 top Republicans, including Texas Sen. Ted Cruz and Georgia Gov. Nathan Deal.

So who was he?

Eugene Yu had just joined the most intriguing primary in the country: the GOP race for Georgia’s open Senate seat. He and at least six other Republicans are vying for the nomination in one of the Senate’s top contests of 2014.

As Democratic recruit Michelle Nunn entered a nearly empty primary field this week, Yu’s candidacy — even as an underdog — is emblematic of the free-for-all that has ensued on the Republican side since Sen. Saxby Chambliss announced his retirement in January.

Other than a clear front-runner, the GOP race has it all — including three sitting congressmen, a minister, a runner-up for the 2010 gubernatorial nomination and three candidates who may be capable of at least partially self-funding.

“It’s getting very interesting here in Georgia,” said Virginia Galloway, the Georgia director of Americans for Prosperity, with a laugh. “Everybody’s running for the Senate.”

Even if the unpredictable primary is a headache for Republicans, GOP sources said they remain confident they will emerge victorious next November. Democrats are also upbeat about the race in the wake of Nunn’s Tuesday announcement — even if everything must go right for them to win.

“It is more incumbent upon us now to nominate somebody who is reasonable and respectable and is going to put the best foot forward for the Republican Party,” Georgia Republican consultant Joel McElhannon said.

Meanwhile, the GOP field grew more unwieldy this week.

David Perdue, the former CEO of Dollar General, officially entered the race on Wednesday. In his announcement video, Perdue played up his business experience to contrast against Reps. Paul Broun, Phil Gingrey and Jack Kingston, as well as former Georgia Secretary of State Karen Handel.

A third wealthy individual considering the race is Kelly Loeffler. She’s the co-owner of Atlanta’s WNBA team and her husband, Jeffrey Sprecher, is awaiting final approval to purchase the New York Stock Exchange.

In a major curveball for the nomination fight, the Justice Department is pushing Georgia to extend to 45 days the amount of time between its primary and runoff to allow military ballots to be fully counted. If there is a change, the primary could be held as early as May.

Kingston’s status as an appropriator will likely be used against him in the race and could affect his chances to win an ideological primary. Broun, who was endorsed by former Texas Rep. Ron Paul, will likely find much of his support in the conservative wing of the GOP, which could be more influential in a midsummer, low-turnout contest.

“If school is still in and average Joe Georgian is still home because his kids are going to school every day … we’re going to have a much larger primary electorate,” said one unaffiliated Republican operative. “And that is going to be terrible for Paul Broun. … The bigger the primary, the better Jack Kingston does.”

Among the candidates already in the race, Kingston nearly doubled what any of his opponents raised in the second quarter, ending the period with $2.3 million in cash on hand. Gingrey had about $2.6 million in cash on hand, Broun had $401,000, and Handel had $150,000 after entering the race late in the quarter.

But those figures could pale in comparison to potential self-funding from other candidates.

Yu, the owner of Continental Military Services, did not return a request for comment. But a source that spoke with him the night of his speech said Yu is aware that most of the money he spends will likely be his own.

“I met him for the first time Friday night,” said Randy Evans, a Republican National committeeman from Georgia, who visited with Yu at a private reception for Cruz. “I think he understands that for him it would have to be largely a self-funded race — zero name recognition.”

McElhannon said Tuesday, before Perdue’s announcement, that Loeffler’s and Perdue’s willingness to spend a significant amount of their own money would be a major factor going forward.

“This last campaign disclosure report shows that Kingston’s the guy that a lot of the Republican money crowd is coalescing behind, at least right now,” he said. “But there are still two big names that would completely scramble the Republican side in Perdue and Loeffler.”

Republicans in the state concede that Democrats now have a candidate to rally around in Nunn, the longtime head of the Points of Light Foundation and daughter of former Sen. Sam Nunn, D-Ga. But they question the first-time candidate’s ability to win a highly contested race in a state where Democrats have seen little recent statewide success — especially with one of the country’s most dysfunctional state parties.

Still, in a Wednesday memo, Guy Cecil, the executive director of the Democratic Senatorial Campaign Committee, acknowledged that the GOP’s unpredictable primary “makes this a battleground contest.”