ATLANTA — The Republican runoff for Georgia lieutenant governor has ended with so few votes separating the candidates that a recount may be needed before a winner is declared.

Unofficial returns show former state Rep. Geoff Duncan finishing just 1,730 votes ahead of state Sen. David Shafer in the Tuesday election. That’s less than 1 percent of the total votes cast in the runoff, which exceeded 556,000.

Georgia law allows for a recount of the vote in any election where the victory margin is less than 1 percent. Shafer of Duluth would have to request a recount in writing.

Duncan of Cumming tweeted “WE WON!” on Wednesday. His campaign website links to the Twitter account that posted the tweet.

Shafer’s campaign did not immediately return phone and email messages.

Shafer has served at the state Capitol since 2002 and once was the Senate's president pro tempore. Duncan spent five years in the House. They're competing for a chance to succeed Casey Cagle in the state's No. 2 elected office, whose main job is to preside over the Senate.

The runoff winner will face Democrat Sarah Riggs Amico, a Marietta businesswoman, in the November general election.

Thornton wins Democratic contest for school superintendent

Democrat Otha Thornton Jr. has been nominated to challenge Georgia’s Republican state schools chief in November.

Thornton of Richmond Hill defeated Sid Chapman of Griffin in a Democratic runoff election Tuesday. Thornton advances to the fall  campaign against Republican state School Superintendent Richard Woods.

Thornton is a retired Army lieutenant colonel who became the first black man named president of the National PTA in 2013. He was endorsed by Arne Duncan, who served as education secretary under President Barack Obama.

His opponent was a former classroom teacher as well as a past president of the Georgia Association of Educators. Chapman had support from former Democratic Gov. Roy Barnes.

Raffensperger wins GOP runoff for secretary of state 

Raffensperger of Johns Creek defeated former Alpharetta mayor David Belle Isle on Tuesday to become the GOP nominee for secretary of state. The office is currently held by Republican Brian Kemp, who passed on seeking re-election to run for governor.

Raffensperger is a lawmaker in the state House and a businessman. He will face Democrat John Barrow of Athens in the fall campaign. Barrow is a former Georgia congressman who lost his seat in 2014.

Both GOP runoff candidates emphasized upgrading Georgia’s electronic voting machines for improved security as their top priority.

The secretary of state oversees elections as well as corporate filings and professional licensing.