Days after three people in Florida and Virginia were charged with voter fraud, Florida's Republican Party is claiming the practice is ongoing in the Sunshine State.

Fox News reported Wednesday afternoon the state's GOP sent a letter to the Broward County supervisor of elections to say people are opening mailed-in election ballots — tens of thousands of them — before they are officially verified, a process known as canvassing.

Fox reported no direct evidence of the practice was in the letter. Florida's GOP is expected to file a lawsuit related to it at 9 a.m. Thursday.

Ballots that are mailed in must be first verified by the state's canvassing board before they are opened and the votes inside are logged. Fox reported this process is not being followed.

Last Friday, Reuters reported two Florida women and a Virginia man had been charged with voter fraud. All three cases were unrelated.

Republican presidential nominee Donald Trump has warned his supporters to be on the lookout for voter fraud at the polls next Tuesday.