The Trump reelection campaign sued Pennsylvania state and county elections officials Monday, saying mail ballot drop boxes were unconstitutional in the way they were used in the June 2 primary election and asking a federal court to bar them in November.

“Defendants have sacrificed the sanctity of in-person voting at the altar of unmonitored mail-in voting and have exponentially enhanced the threat that fraudulent or otherwise ineligible ballots will be cast and counted in the forthcoming general election,” says the suit, filed in the U.S. District Court for the Western District of Pennsylvania.

Instances of voter fraud are rare, and there is virtually no evidence of successful widespread conspiracy to commit fraud via mail ballots. (An alleged effort in Paterson, N.J., last month quickly raised flags, and last week the state attorney general charged four men in the scheme.)

The lawsuit says mail ballot drop boxes violate the state and federal constitutions because elections officials are making decisions outside of what the law allows, taking the power to make law away from the legislature. The suit also argues that state and county elections officials set up different rules and policies across the state, creating a patchwork system that violates constitutional guarantees of equal protection.

The Republican lawsuit comes as President Donald Trump has escalated his attacks on voting by mail, raising unfounded claims of voter fraud and invoking conspiracy theories about foreign interference in mail voting. While voting by mail generally has not been shown to benefit one party over the other, the issue has become partisan. In Pennsylvania most Democrats voted by mail in the primary, while most Republicans voted in person.

Joining the Trump campaign in the lawsuit are the Republican National Committee; Republican U.S. Reps. Glenn Thompson, Mike Kelly, John Joyce, and Guy Reschenthaler, all from Pennsylvania; and two Republican voters who want to serve as poll watchers in November. The defendants are Kathy Boockvar, Pennsylvania’s secretary of state, and all 67 counties’ boards of elections.

The Pennsylvania Department of State, which oversees elections, declined to comment.

Democrats immediately accused Republicans of attempting to suppress votes.

”Donald Trump and Washington Republicans are trying to suppress the voices of Pennsylvanians because they know the easier it is for everyday people to vote, the more likely it is that they will lose,” Sinceré Harris, executive director of the state Democratic Party, said in a statement.

Mail ballot drop boxes are largely new to the state. Pennsylvania long had a restrictive absentee ballot system in which only about 5% of votes were cast by mail. But a new law allowed any voter to request a mail ballot beginning with this year’s primary. The coronavirus pandemic then fueled a massive surge in mail voting.

But it soon became clear that county elections offices were struggling to keep up with voter demand for mail ballots, and counties scrambled to set up drop box locations. Because Pennsylvania law requires mail ballots to be received by county elections officials by 8 p.m. on an election day, the idea behind the drop boxes was to allow voters to hand-deliver their ballots and know they had been received on time.

The lawsuit says this violates state law because ballots are supposed to be directly delivered to county elections offices.

“Permitting absentee and mail-in ballots of nondisabled electors to be collected at locations other than the offices of the county boards of elections and/or through ‘drop boxes’ and other unmonitored and/or unsecured means and to be counted when not cast in the manner mandated by the Election Code allows illegal absent and mail-in voting, ballot harvesting, and other fraud to occur and/or go undetected, and will result in dilution of validly cast ballots,” the suit says.

It also says some counties violated state election law by counting mail ballots that were sent without secrecy envelopes, which are placed inside mailing envelopes and help keep ballots anonymous. In addition, the lawsuit argues the state should allow voters to serve as poll watchers in counties other than where they live.

The lawsuit is the latest in a series of legal challenges to electoral systems in Pennsylvania and elsewhere, as Democrats and Republicans try to change the rules before November. Democrats and liberal-leaning groups have sought to extend mail ballot deadlines in Pennsylvania, for example, as well as other voting expansions in other states.

While all elections are messy, complicated affairs, administering them this year has proven to be a monumental task, with Pennsylvania officials contending with new voting machines, high-interest presidential election turnout, the coronavirus, and the most significant election law changes in decades. The ongoing litigation means some details of how the November election is run may yet change in the four months before Election Day.

That could have a significant impact on how votes are cast and counted. Even small differences matter. In 2016, Trump won the state by 44,000 votes, or less than 1% of the votes cast.