SEATTLE — Less than a year after Oregon’s Senate Republicans fled the state with passports in hand and hid out in Idaho cabins to avoid voting on a climate change bill, they have disappeared again.

With Democrats seeking to advance a new proposal to cap the state’s greenhouse gas emissions, most Republicans refused to attend a floor session on Monday morning, and a search by the Senate chamber’s sergeant-at-arms failed to find them.

That left the Senate with just 19 members on the floor — one short of a quorum needed to vote — and threatened to derail a range of bills in the final two weeks of the state’s legislative session.

Senate President Peter Courtney, a Democrat, called on senators to return to work, saying the climate bill had sufficient votes to pass in a chamber with a large Democratic majority.