ATLANTA (AP) — Georgia lawmakers are considering replacements for the state's touch-screen voting machines that were adopted statewide 15 years ago and that have been criticized because they don't produce a paper trail.

The state House Science and Technology Committee heard on Thursday from representatives of three different voting technology companies.

"We're just trying to understand what options the state of Georgia has," said state Rep. Ed Setzler, a Republican from Acworth who chairs the bipartisan panel.

Critics of Georgia's voting machines have said they're highly susceptible to being rigged by hackers in all-but-undetectable ways and that their votes can't be reliably recounted. They've urged the state to review and replace the voting system.

There's no timeline for replacing the current system, and Setzler said he wants to proceed carefully so the state has the information needed to choose the best option to make elections as credible and secure as possible. He said he's not concerned about getting new machines by next year's midterm elections.

"In spite of criticism and innuendo, I think there's been many elections where this system has proven itself," Setzler said of the current machines.

But state Rep. Scot Turner, a Republican from Holly Springs who also sits on the committee, said he still thinks it's possible that the state could have a new system in place by November 2018, though he conceded that would be a stretch.

"I'm hopeful we will make a case that will create the urgency required for a change," he said after the hearing.

Susan Greenhalgh with Verified Voting, a non-partisan, non-profit organization that pushes for measures to make elections accurate, transparent and verifiable, said after the hearing that system the state currently uses is old, has raised security concerns and has already been abandoned by other states for that reason.

"The time is now for Georgia to fix their voting system," she said. "It's good the legislature is taking this up and we hope they move quickly."

The three companies the committee heard from are: Election Systems and Software, based in Omaha, Nebraska; Denver-based Dominion Voting; and Hart InterCivic, based in Austin, Texas.

The company representatives walked the lawmakers through different voting systems, including touchscreen machines that produce a paper record that is then scanned and paper ballots that are filled out by hand and then fed into an optical scanner.

Greenhalgh told the committee that her group, which was founded by computer scientists, doesn't endorse a specific vendor but recommends that states use paper ballots completed by hand and then read by an optical scanner. Much of the rest of the country has already moved to that option, she said.

The low-tech nature of a power ballot makes them reliable even in the case of an event like a power outage, and it's also a cheaper option because the state would only need to buy a scanner for each polling place, rather than multiple individual voting machines, she said.

It's not just Georgia's touch-screen voting machines that have drawn criticism.

A server at the Center for Election Systems at Kennesaw State University, which manages voting state wide, drew national attention in June after a security expert disclosed a security hole that wasn't fixed six months after he reported it to election authorities. The researcher said he found a directory open to the internet that contained not just the state voter database, but PDF files with instructions and passwords used by poll workers to sign into a central server used on Election Day.