Democratic organizations filed lawsuits in Georgia, Arizona and Texas on Friday saying Republicans are given an unfair advantage by being listed first on those states’ general election ballots.

The traditionally red states Democrats hope to make competitive in 2020 have slightly different rules about ballot placement, but in each case, because Republicans control the governorships, every other race from president on down is listed with the Republican candidate first.

“We know from the social science that there is something called the ‘primacy effect,’ studied across all kinds of things that have nothing to do with politics,” said Marc Elias, a Washington-based Democratic attorney. “This is putting an invisible thumb on the scale for the Republican candidate.”

Ahead of 2020, Democrats are looking at a slew of election laws they believe could tip the scale in Republicans’ favor, filing lawsuits all over the country over matters like voting access for college students and ballot order. The Democratic National Committee, Democratic Congressional Campaign Committee, Democratic Senatorial Campaign Committee, Priorities USA and states’ Democratic parties are involved in the lawsuits filed Friday.

The DNC and other party-affliated groups filed a similar lawsuit in Florida in July decrying ballot order bias they contend would give President Trump the edge in a crucial battleground state he won in 2016 by only 1.2 percentage points.

The 2018 Democratic candidates in Florida for governor and U.S. Senate lost by razor-thin margins to GOP opponents whose names were listed first, a factor Elias said may have made a difference to the outcome.

Democrats suggest it would be fairer in these states where races tend to come down to a percent or two difference that the ballot order rotate by precinct or county to avoid giving one party preferential treatment.

In Georgia, Democrat Stacey Abrams lost her race for governor in 2018 by 1.6 percentage points. In Texas, former Democratic congressman Beto O’Rourke lost his Senate race to incumbent GOP Sen. Ted Cruz by 2.6 percentage points.

The ballot placement rules, the lawsuits argue, are unconstitutional because they violate the 14th Amendment’s Equal Protection Clause by treating “similarly-situated major-party candidates differently.”

The Democrats’ case against the law in Florida was met with resistance from state and national Republicans who argued Democrats did not have merits in the case, but merely were upset they have lost the state in recent elections.

A spokesman for the National Republican Senatorial Committee, the GOP group that joined the defense of the Florida ballot order law, did not immediately respond to request for comment about the latest Democratic lawsuits.