NASHVILLE, Tenn. (AP) — Democratic U.S. Rep. Jim Cooper on Friday urged Tennessee's Republican-led legislature to use $29 million-plus in federal money to require backup paper ballots for elections, citing concerns from national security experts that paperless systems could be vulnerable to hacking from Russia and others.

Though Cooper isn't sure how much adding a paper trail would cost, the Nashville congressman said the leftover federal Help America Vote Act money could help secure the ballots, possibly in time for the local primaries in May. Tennessee largely uses paperless machines.

"We have an opportunity to improve our election system so that it cannot be hacked, so the voters have complete faith in the integrity in the system, so that democracy works well here in Tennessee," Cooper told reporters Friday.

A state bill by Democratic Senate Caucus Leader Jeff Yarbro of Nashville that would require the backup paper records by 2020 is slated for a committee hearing Tuesday.

It's unclear whether it will get serious consideration, partly because the concept hasn't drawn the same calls for quick adoption from state elections officials.

Adam Ghassemi, Tennessee Secretary of State Tre Hargett's spokesman, said counties choose from state- and federally certified machines, equipment changes are typically done during nonelection years and machines also aren't connected to the internet. Officials have said Tennessee wasn't one of the 21 states notified by the U.S. Department of Homeland Security last year about attempted system breaches by Russians in the 2016 elections.

Ghassemi said results certification in the weeks following elections helps to add a layer of checks and balances.

Last month, Hargett told a state legislative panel that there is uncertainty in the states while legislation on voting equipment is pending in Congress.

"Frankly, we're probably trying to slow down a little bit because that federal legislation could mandate that we purchase certain types of machinery," Hargett said.

Cooper said the need is immediate, given that Tennessee has open races for U.S. Senate race and governor, and a big referendum on transit funding in Nashville this year.

Cooper said he hoped the urgency would come across as Hargett and state Coordinator of Elections Mark Goins attend national conferences for elections officials this week on topics that include election cybersecurity.

Former Director of National Intelligence James Clapper, ex-Secretary of Homeland Security Michael Chertoff and others have encouraged the use of ballots that provide a paper trail.

Chertoff joined conservative activist Grover Norquist to write a column in The Washington Post calling for paper ballots that can be audited.

"The best estimates show that we can replace all paperless voting machines in the United States for about the cost of a single F-22 fighter jet — and in fact, the Senate bill would not add to the deficit because it offsets any new spending," the column says.

Cooper's call came as an indictment came down Friday against 13 Russians, including a businessman close to Vladimir Putin, in what prosecutors say is an elaborate plot to interfere in the 2016 U.S. presidential election through social media propaganda.

The indictment says one of the Twitter accounts created and run by the Russians, "Tennessee GOP," falsely claimed to be controlled by the state party. Under the handle of @TEN_GOP, the account gained more than 100,000 followers and in one instance, posted that allegations of voter fraud were being investigated in North Carolina, the indictment says.