SALT LAKE CITY (AP) — A pair of pro-marijuana groups in Utah are threatening to sue over a special session scheduled for next month when a medical marijuana ballot measure passed by voters will be revised as part of a compromise reached before the election.

The groups allege in a letter sent Thursday that the Mormon church is using its power to unfairly gut the initiative.

The letter was also sent to the main groups backing the marijuana initiative who agreed to the special session as part of a pre-election compromise with The Church of Jesus Christ of Latter-day Saints, the governor and state lawmakers.

Eric Hawkins, spokesman for The Church of Jesus Christ of Latter-day Saints, didn’t immediately have comment.

The faith opposed the ballot proposal, but agreed to the deal to allow access for people with serious medical needs.