(CNN)Democratic Sen. Bill Nelson's re-election campaign has filed a lawsuit against Florida Secretary of State Ken Detzner over vote-by-mail ballots and the process used to validate them.
Bill Nelson's campaign sues Florida secretary of state as vote count fight continues
Democratic lawyer Marc Elias, the lead recount lawyer for Nelson, decried the signature matching process that is used to validate provisional ballots, arguing that it leaves the decision to the "untrained opinions" of poll workers to determine "whether signatures match." He said there was a "complete lack of uniformity" in how those signatures were judged.
"This serves as an outright disenfranchisement and burden on the right to vote," Elias told reporters on a call Friday.
The lawsuit comes amid a bitter fight between Republicans and Democrats in the state over multiple electoral contests, including Nelson's race for re-election and the gubernatorial contest between Democrat Andrew Gillum and Republican Ron DeSantis. The Republican candidates' leads in both contests are narrowing as votes continue to be counted.
Democrats believe there are enough votes out to tip the Senate race towards Nelson, but are less confident in Gillum's race, where the divide is around 37,000 votes in DeSantis' favor.
Former Democratic Rep. Patrick Murphy tweeted Friday that he was among the voters whose ballots weren't counted because of an "invalid signature."
"Hey @MarcACaputo, just saw notice from @PBCounty that my absentee ballot wasn't counted due to 'invalid signature' match," he said. "Should be +1 @NelsonForSenate @AndrewGillum. Must overhaul these ridiculous barriers to voting."
Florida law mandates that any races within .5% would go to a machine recount. For those races that are within .25% after that machine recount, a hand recount would be initiated of ballots marked as undervotes (voters who did not fill out all available choices on the ballot) or overvotes (voters who made more choices than allotted on the ballot). The hand recount would only occur if there are enough overvotes, undervotes and provisional ballots left to change the outcome.
At the center of the battle is Detzner, a Republican who was appointed by Florida Gov. Rick Scott, Nelson's GOP opponent in the contested Senate race.
The lawsuit, brought by Nelson's campaign and the Democratic Executive Committee of Florida, asks for all votes cast using vote-by-mail or those "determined to involve a signature mismatch, be counted as valid votes."
"This entirely standardless, inconsistent, and unreliable signature matching process, which has a disparate impact on People of Color and young, first time voters, violates the prohibition against undue burdens on the right to vote, enshrined under the First and Fourteenth Amendments to the U.S. Constitution, and subjects Florida voters to disparate treatment and inconsistent standards in violation of the Fourteenth Amendment's Equal Protection Clause," reads the lawsuit.
Elias opened a call with reporters on Friday by highlighting how the split between Scott and Nelson has shrunk since Election Day and confidently said he believed, after all votes are counted correctly, Nelson would prevail the winner.
"I would expect when we go into a machine recount and then a hand recount, right now the results are unknown who has won, and if I had to place a bet, I w