SALEM, Ore. — Oregon Senate Republican Leader Herman Baertschiger, Jr. chided the Democrats for closing the State Capitol building over the weekend.

Protesters showing support for Oregon Senate Republicans who have walked out in opposition to HB 2020, a cap-and-trade energy conservation bill, rallied at the Capitol building on Saturday and Sunday.

Saturday's rally was scheduled to coincide with Saturday's Senate session, but the Capitol was closed following a "possible militia threat" at the rally, according to a spokeswoman for Senate President Peter Courtney.

Oregon State Police, in a statement Saturday, said it had been "monitoring information throughout the day that indicates the safety of legislators, staff and citizen visitors could be compromised if certain threatened behaviors were realized."

On Sunday morning, the State Senate sessions lasted only a few minutes. With only 18 members on hand, there weren't enough in attendance for a quorum, so Courtney adjourned for the day. Democrats have an 18 to 12 majority in the chamber, but they need 20 members present for a quorum.

At around 10 a.m., Oregon State Police troopers closed down the Capitol building after a group of protesters went inside planning to sing the national anthem in the rotunda.

"No one is causing any trouble," said protester Wayne Nehl of Silverton, who works in the trucking industry and attended Sunday's rally. "It's just an orderly protest-type situation."

WATCH: Protesters gather Sunday morning at the Oregon State Capitol

Baertschiger, Jr. released a prepared statement Sunday criticizing the Democrats for canceling Saturday's session and closing the Capitol building.

"Democrats were reactionary to rumors and lacked the courage to face these Oregonians by closing the Capitol building on Saturday, when it was scheduled to be open, and limiting space in the gallery of the Senate Chamber, forcing them into committee rooms to watch the floor on Sunday," he wrote in a prepared statement released Sunday. "My caucus and I continue to stand firm and remain out of the state. We are working for our constituents and all Oregonians."

Last week, Republican state senators fled the Legislature — and some, the state — to deny the majority Democrats enough votes to take up the cap-and-trade bill, which would dramatically reduce fossil fuel emissions by 2050. It would be the second program of its kind in the nation after California if passed.

Gov. Kate Brown then dispatched the state police to round up the rogue lawmakers, but none have been located.

RELATED: Gov. Brown sends police to find walkout GOP senators: ‘They need to return and do the jobs they were elected to do’

Under the proposed cap-and-trade bill, Oregon would put an overall limit on greenhouse gas emissions and auction off pollution "allowances" for each ton of carbon industries plan to emit. The legislation would lower that cap over time to encourage businesses to move away from fossil fuels: The state would reduce emissions to 45% below 1990 levels by 2035 and 80% below 1990 levels by 2050.

Read HB 2020, the cap-and-trade bill

Those opposed to the cap-and-trade plan say it would exacerbate a growing divide between the liberal, urban parts of the state and the rural areas. The plan would increase the cost of fuel, damaging small business, truckers and the logging industry, they say.

Many of those who attended Sunday's rally said they want the public to be able to vote on the bill, instead of the decision being made by legislators.

"We're playing a political game here and going past the people, calling it an emergency," Nehl said. "This is another thing that will affect Oregon's economy and small business all over the state."

Another protester at Sunday's rally, Cindy Stoeckler of Washington County, agreed.

"They won't bring it to the vote of the people and people need to be educated. It will affect every single Oregonian," she said.

Democrats say the measure is an efficient way to lower emissions while investing in low-income and rural communities' ability to adapt to climate change. It has the support of environmental groups, farmworkers and some trade unions.

California has had for a decade an economy-wide cap and trade policy like the one Oregon is considering. Nine northeastern states have more limited cap-and-trade programs that target only the power sector.

Watch: What is cap and trade?

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