Update, Jan. 30: Georgia's rules might not be changing after all for a special U.S. Senate election featuring appointed incumbent Kelly Loeffler, U.S. Rep. Doug Collins, the Rev. Raphael Warnock and others.

Current law holds that all candidates, Republican and Democrat, would run against each other on the November ballot, with a January runoff if no one wins a majority.

House Bill 757 would change Georgia law to require primary elections to determine each party's nominees ahead of the special election. On Thursday, the rules committee decided it needs more work.

The measure backed by House Speaker David Ralston, a Collins ally, would help the congressman by forcing Loeffler into a May primary and shortening her time to build a record to run on. Gov. Brian Kemp, who appointed Loeffler, has threatened to veto the measure.

Many Democrats also favor a primary. It could allow Warnock to consolidate the support of Democratic voters and cut the chance of a lower-turnout January runoff where Democrats might be at a disadvantage.

Governmental Affairs Chairman Shaw Blackmon, a Republican from Bonaire, said after Thursday's vote that lawmakers would like to look at including primaries for legislative special elections, which aren't currently covered, as well as to get input from Secretary of State Brad Raffensperger. Blackmon said he wasn't sure when or if the bill might re-emerge.

Previous story: ATLANTA — Newly appointed U.S. Sen Kelly Loeffler could face an unexpected GOP primary later this year in her quest to hold onto her seat under a bill passed Monday by a Georgia legislative committee against the wishes of the state's Republican governor.

The move could ease the way for GOP U.S. Rep. Doug Collins or another Republican to run against Loeffler, who was hand-picked by Gov. Brian Kemp even though Collins was President Donald Trump's preferred pick. The measure could  also improve the chances for a Democrat to wrest the seat away from Republican control.

Under current Georgia law, Loeffler and any other candidates, regardless of party, would run together in a November special election. If no one wins a majority of the vote, a runoff would be held in January — with control of the Senate potentially in the balance.

House Bill 757, which would establish May primaries, passed Monday out of the Elections Subcommittee of Georgia's House Governmental Affairs Committee on an 8-2 vote. Democrats joined most Republicans to vote yes, and only two Republicans voted no.

The measure still has a long way to go before it would become law, and Kemp promptly issued a veto threat.

"You don't change the rules at half-time to benefit one team over another," spokeswoman Candice Broce said in a statement. "People are sick and tired of it. The Governor will veto any bill that attempts to undermine the rule of law for perceived political gain."

Kemp appointed Loeffler after Sen. Johnny Isakson retired because of health reasons. The governor is backing the wealthy businesswoman in her attempt to win the remaining two years on Isakson's term.

The measure that was considered Monday could set up a showdown between Kemp and powerful Republican state House Speaker David Ralston of Blue Ridge. Ralson issued a statement Monday supporting the proposal to add party primaries to the race for Loeffler's seat, saying it "provides voters with order and certainty." 

"The underlying principle of this legislation is a fair, comparable playing field for all those seeking elected office," Ralston said. "Surely that is something we can all agree on."

The measure under consideration Monday started out as an attempt by Republican Secretary of State Brad Raffensperger to seek legal clarification of when the sign-up period for a special election should be set. An early deadline for candidate qualifying could help Loeffler by weeding out potential challengers before they can get organized. A later qualifying date could allow surprise entrants, such as Democrats now running against U.S. Sen. David Perdue who might lose that primary on May 19.

As changed in the subcommittee, the bill would require the primary for the special election to also be held May 19. Qualifying would close no later than March 20. Raffensperger has said he wants qualifying for the Senate election to be during the first week in March, when qualifying for other state and federal offices is scheduled.

Rep. Barry Fleming, a Harlem Republican who introduced the bill on Raffensperger's behalf, voted against the changes and the bill's subcommittee passage. He said that he generally favored party primaries, but opposed making the change now.

"My preference is that it be in a separate bill, and this be a clean bill," Fleming said.

Rep. Scot Turner, a Holly Springs Republican, said he was opposed to changes because it appeared to try to change the law based on what Ralston wanted. Collins was an ally of Ralston's when Collins served in the state House.

"I get really hesitant when we start changing law around here because of one person's opinion," Turner said.

Democrats were happy to join in, though. The measure would drastically reduce the possibility of a Jan. 5 runoff, widely seen as a disadvantage to Democrats.

"The voters in the respective parties can make their decisions and then we can have a clarifying general election," House Minority Leader Bob Trammell, a Luthersville Democrat, told reporters after the vote.

So far, two Democrats have announced plans to challenge Loeffler. Matt Lieberman is an Atlanta educator and the son of former vice presidential candidate Joe Lieberman. Ed Tarver of Augusta served as U.S. attorney for Georgia's Southern District during President Barack Obama's two terms.

The Rev. Raphael Warnock, who pastors the Atlanta church once led by Martin Luther King Jr. and his father, is considering a bid and could announce soon. He's widely seen as the favorite of party leaders, and a primary could allow the winner to consolidate party support.

Collins, one of Trump's most vocal advocates among Republicans in the U.S. House, has said he's considering a challenge to Loeffler.