ROSWELL, Ga. -- Elections officials say they are taking steps to ensure the security of voting Tuesday in the sixth congressional district race. It’s gotten national attention, and it was the apparent motive behind a dozen threatening letters discovered Thursday.

The threats appeared in the mailboxes of residents living near Republican congressional candidate Karen Handel, and the candidate herself. They also appeared in the mailrooms of two media outlets – WXIA and WAGA-TV.

They all contained computer-printed rants against Handel and President Donald Trump. And some contained a powder identified in some of the notes as anthrax – but which authorities believe was actually baking soda.

The US Postal Service intercepted some of the letters before they were delivered. There were a dozen total, postmarked in Greenville, SC.

"There is commonality among these letters," said FBI spokesman Steve Emmett. "Right now, these letters seem to have originated from the same individual or individuals."

Two of the letters promise to “finish off the survivors with a hail of bullets.” The letters did not specifically threaten voters. But they cast an uneasy cloud over an almost sacred process that will decide the sixth district race Tuesday.

"After the baseball field shooting of (Rep. Steve) Scalise, I don’t know," said Anne Horne, an early voter at the East Roswell Library Friday. "There are nutjobs all over the place. You just never know when a lone person will turn a little crazy."

Fulton, Cobb and DeKalb counties will send voters to 155 voting precincts Tuesday. Elections commissioners in each county told 11Alive News Friday they are addressing potential security concerns in light of the threats – without revealing too many specifics.

At the East Roswell library, early voters say balloting felt routine. "I don’t see anything. I’m aware of everything. I don’t see anything," said Britt Peace, an early voter. "Looks like it’s pretty safe to me."