President Trump’s campaign and three Republican groups are suing Montana Gov. Steve Bullock (D) over his directive last month allowing counties to conduct mail-in voting. 

The suit, filed in the U.S. District Court in Helena on Wednesday by Trump's campaign, the Republican National Committee, the National Republican Senatorial Committee and the Montana Republican State Central Committee, argues Bullock’s directive is an illegal “power grab” by the Democratic governor, who is also running for Senate in November’s election.

“The Governor’s power grab under the cover of COVID-19 is particularly egregious. The Governor is running for U.S. Senate as a member of the Democratic Party and his race is one of the most competitive in the country," the suit states, according to the Independent Record. "So he is using his current position to force a brand-new election system on Montanans that, according to his own party, will sway the election in his favor. This action cannot stand."

The lawsuit also named Montana Secretary of State Corey Stapleton, who is a Republican, according to the Record. 

Bullock defended his directive in a statement responding to the lawsuit. 

“Voting by mail in Montana is safe, secure, and was requested by a bipartisan coalition of Montana election officials seeking to reduce the risk of COVID-19 and keep Montanans safe and healthy,” the governor said in a statement. “This is the same directive that the Republican President of the Senate and Republican Speaker of the House said was the right thing to do for the June primary. Today, we have many more active cases of COVID-19 than we did back in June.” 

He also said the lawsuit “appears to be part of a pattern of lawsuits across the country by Republican party operatives to limit access to voting during the pandemic.” 

A spokesperson for Stapleton was not immediately available for comment. 

The Trump campaign has similar lawsuits filed against New Jersey and Nevada for planning to send mail-in ballots to all state voters, CNN notes. 

The Trump campaign also filed a lawsuit in Pennsylvania against the state over how it sends and counts mail-in ballots, but a U.S. district court judge last month halted the suit. 

Trump has slammed mail-in voting efforts for months, making unsubstantiated claims that it leads to widespread voter fraud. Democrats, however, have largely pushed for an increase in mail-in voting methods in an effort to provide alternatives to traditional in-person voting amid the coronavirus pandemic.