By JONATHAN MATTISE, Associated Press

NASHVILLE, (AP) - Amid growing national concerns about election security, Tennessee's three largest counties plan to begin using voting machines that produce a voter-verifiable paper trail in time for the 2020 presidential primaries.

The Republican-led state doesn't require the change. Secretary of State Tre Hargett says he's letting counties decide whether to switch.

Only 14 Tennessee counties, with 556,400 registered voters combined, used voting equipment with a paper trail in 2018.

Those looking to switch include Shelby County, anchored by Memphis; Davidson County, encompassed by Nashville; and Knox County, which includes Knoxville. They account for 1.3 million of Tennessee's 4.16 million registered voters.

Cybersecurity experts have long complained that the nation's antiquated elections infrastructure is vulnerable to tampering - especially paperless equipment.

Hargett has contended that either type of machine is secure.

Copyright 2019 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.