Oregon’s state Senate has cancelled its session scheduled for Saturday, citing a “credible threat” from militia groups over the showdown between the state’s Democratic legislators and GOP senators.

The Oregon Capital Bureau obtained an email from the Senate’s Democratic caucus telling its members on Friday to stay away from the Capitol on Saturday.

“The State Police superintendent just informed the Senate president of a credible threat from militia groups coming to the Capitol tomorrow,” the email read. “The superintendent strongly recommends that no one come to the Capitol and President Courtney heeded that advice minutes ago by adjourning until 10 a.m. Sunday. Please make sure your staffs know not to come in tomorrow.”

This latest development is a dramatic escalation of the ongoing conflict roiling in Oregon’s state government.

It began on Thursday when Republican senators fled the state to avoid voting on a sweeping cap-and-trade bill aimed at reducing carbon emissions. Gov. Kate Brown (D) responded by authorizing the state police to fetch the lawmakers.

Then right-wing militia groups publicly announced that they would provide refuge for the fleeing Republicans.

“These people are all armed and prepared to put themselves in front of senators to prevent arrests from Oregon State Police specifically,” a member of the Oregon III% organization told TPM.

A representative for the Senate’s GOP caucus told TPM on Friday that the senators “are not with any militias.”