(CN) – Democratic organizations and activists claim in court that Florida’s “ballot order” law unfairly puts their candidates at a disadvantage by listing Republican candidates first year after year.

In a federal lawsuit filed in Tallahassee, the Democrats contend the statute mandating candidates of the governor’s political party to be listed first on a ballot creates “position bias” and gives the governing party an unfair advantage.

The Democratic National Committee, Democratic Governors Association, Democratic Legislative Campaign Committee and the liberal group Priorities USA brought the suit against Florida Secretary of State Ken Detzner.

Three Democratic activists joined the lawsuit as plaintiffs, asserting their votes were diluted by the Republican Party’s “artificial and unfair advantage.”

“There is ample evidence proving that the candidate listed first receives a significant number of additional votes due solely to their position on the ballot,” said Marc Elias, lead counsel for the plaintiffs, in a statement provided to Courthouse News. “Florida’s law serves no state interest – rather it creates an environment where Republican candidates benefit simply as a result of their position on the ballot.”

Florida Republicans gain nearly 3 percentage points over the Democratic contender when listed first on the ballot, according to the complaint.

“These numbers are both statistically and electorally significant,” the 40-page complaint states. “Florida’s recent history is littered with examples of elections that were decided by smaller margins.”

But this only accounts for gains, not Democratic losses for not appearing first, the suit says. The real percentage gap between candidates in two-party, two-candidate elections reaches 5 percent, the complaint claims.

The Democrats are asking the court to declare the ballot order law unconstitutional and scrap the statute before this year’s November elections.

Florida’s ballot procedures are not unique. About a dozen other states have similar laws, according to an analysis by the University of Virginia’s Center for Politics.

Geoffrey Skelley, a political analyst with the center, said most studies agree there is some positive effect for candidates listed first, but disagree on the size of the effect.

“In big ticket races, there is less of an effect, because obviously the voters are better educated on these particular offices,” Skelley said. “It’s as you get down the ballot in the races where there’s less information and the voters are not familiar with the candidates.”

Non-partisan races show the most position bias, he added.

Florida Secretary of State Detzner’s office did not immediately respond to requests for comment by phone and e-mail.