The vast majority of Oregon Republican state senators on Monday walked out of the Capitol and prevented the state’s upper chamber a quorum to vote on a bill designed to cap greenhouse gas emissions.

The walkout mirrored moves Republican legislators made last year as they looked to stop the passage of a similar measure and threatens to upend the remaining weeks of the state's legislative session.

Oregon Gov. Kate Brown (D) denounced the vote "boycott" during a news conference, saying that if Senate Republicans "don’t like a bill, they need to show up and change it or show up and vote no."

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"This makes it very, very clear. The Senate Republicans who walked out are not against climate policy. They are against the democratic response," she said. "Oregonians should be outraged."

Just one GOP state senator showed up to Monday morning's Senate floor session after the legislature's Ways and Means Committee advanced the bill, according to The Oregonian. Senate President Peter Courtney (D) was forced to adjourn the the chamber after a sergeant-at-arms searched the Capitol without finding any of the other 11 GOP senators.

Two-thirds of senators are required to be present for the Senate chamber to move forward with a vote, according to Oregon's state constitution. Democrats occupy 18 of the 30 seats, meaning they needed just one more Republican in attendance for a vote.

Senate Republican Leader Herman Baertschiger Jr. said in a statement that Courtney's actions in the committee left lawmakers no choice but to "boycott and deny quorum." Courtney joined the committee early Monday to provide a crucial vote allowing the legislation to advance, The Oregonian noted.

Baertschiger claimed that Democrats refused to work with Republicans on areas of the bill and "denied every amendment that was presented."

The legislation at issue would reportedly set stricter caps on statewide carbon dioxide emissions over time. It would also take aim at business sectors that the state views to be the primary contributors to greenhouse gas emissions.

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Courtney said that Baertschiger "did leave the door open" to returning to the Capitol. But he said it was unclear whether he'd come back unless the cap-and-trade plan is referred to voters.

A group of Republican legislators left the Capitol last year as part of a protest against a sweeping bill proposing a statewide carbon cap. The lawmakers returned after Democrats acknowledged that they didn't have the support to pass the measure.

Oregon Senate Democrats have defended the new measure as a response to the climate crisis.