The head of the Montana Republican Party wrote an emergency plea this week warning that legislation allowing residents to cast mail-in ballots would benefit Democrats and make it more difficult for the GOP to maintain control of state politics.

At issue is legislation introduced by Montana state Sen. Steve Fitzpatrick (R) that would allow Montanans to cast mail-in ballots in a special election later this year to fill the U.S. House seat vacated by Rep. Ryan Zinke (R-Mont.), whom President Donald Trump tapped to lead the Interior Department. Fitzpatrick introduced the bill to save the state $500,000 by not requiring election judges and other officials to be hired on short notice, he told The Associated Press.

But the legislation prompted Jeff Essmann, the chair of the Montana GOP, to send Republicans an “emergency report” email on Tuesday, warning that making it easier to vote would benefit Democrats.

“All mail ballots give the Democrats an inherent advantage in close elections due to their ability to organize large numbers of unpaid college students and members of public employee unions to gather ballots by going door to door,” Essmann wrote. “Vote-by-mail is designed to increase participation rates of lower propensity voters. Democrats in Montana perform better than Republican candidates among lower propensity voters and Republicans do better among higher propensity voters.”

As states across the country debate voting measures, Essmann’s email provides a remarkably candid glimpse of a Republican official opposing a measure to make it easier to vote on the grounds it would harm his party politically.

While the current legislation only addresses one special election, Essmann warned that it could have severe consequences for the state GOP.

“I know that my position will not be popular with many fiscally conservative Republican County Commissioners or the sponsor of House Bill 305. They may be well intended, but this bill could be death of our effort to make Montana a reliably Republican state,” he wrote. “It is my job to remind us all of the long term strategic advantage that passage of this bill would provide to our Democrat opponents for control of our legislature and our statewide elected positions.”

Essmann did not immediately respond to a request for comment. On Twitter this week, he suggested that Democrats would “intercept” mail-in ballots.

The only voters being suppressed in SB305 are the ones who want to vote at the polls where the Democrats can't intercept their ballot #mtpol https://t.co/zpVYi2Knkk — Jeff Essmann (@EssmannJeff) February 23, 2017

Montana Secretary of State Corey Stapleton, a Republican, voiced similar concerns to lawmakers earlier this week and pointed to the three states that currently have mail-in balloting.

“If you look at the three states that have done it, you can see that populism and direct democracy at its best, all three states — Oregon, Washington and Colorado — they do all-mail-in ballots and they’re all marijuana-all-the-time states too,” he said, according to the Bozeman Daily Chronicle.

The bill was voted out of committee on Wednesday and is now awaiting consideration by the full state Senate.