Florida's State Department reported some voters were being targeted with fraudulent efforts meant to keep them home on Nov. 6, CBCNews.com reported.
Chris Cate, the department's communications director, said between 50 and 100 Floridians in at least 28 counties recently got letters telling them questions had been raised about their citizenship and right to vote. The letters, printed on phony letterhead from Supervisor of Elections Kathy Dent, told recipients to return voter eligibility forms within 15 days of receipt.
"A non-registered voter who casts a vote in the state of Florida may be subject to arrest, imprisonment, and/or other criminal sanctions," the letter said.
Cate said the letters have shown up across the state, While Democrats and independent voters have gotten them, Cate said a "significant majority" of recipients are Republicans.
The FBI is working with Florida law enforcement to investigate the letters, CBCNews.com reported.
Cate also said a handful of voters have received calls during which they were told they could vote by phone, which is "not true whatsoever."
Similar complaints were reported in Virginia, another battleground state. Earlier this month, state election officials said they received complaints from voters who said they'd gotten phone calls telling them they could vote by phone, CBCNews.com said.