Speaking on Earth Day, Inslee said lawmakers have done “zero” for the environment this year. “An absolute goose egg,” he said.

The regular session ends Sunday, but the governor and many lawmakers assume the Legislature won’t produce a 2015-17 budget by then.

Inslee said legislators can redeem themselves by taking advantage of a special session to pass a carbon-reduction bill.

“We have to act to restrain this existential threat to the state of Washington,” he said.

Neither the Democratic-controlled House nor the GOP-ruled Senate has approved Inslee’s proposal to cap greenhouse gases from some 130 businesses, including one fertilizer plant and eight food processors. The businesses, which emit at least 25,000 metric tons of carbon a year, would have to bid for a limited number of carbon credits to continue operating. The number of credits available would gradually be cut in half by 2050.

The Office of Financial Management estimates the auctions would cost businesses $1.2 billion in the first two years, though the agency notes that nobody knows exactly what credits will cost once the bidding starts. “If the auctions generate higher prices than those assumed here, the expenditure impact of the bill could increase substantially,” according to a OFM report.

Lawmakers also haven’t embraced Inslee’s proposal to lower the “carbon intensity” of gasoline and diesel. Supporters and critics of the policy disagree whether promoting ethanol and other biofuels would add a dime or a dollar to a gallon of fuel.

Republican lawmakers say they and their constituents can’t live with the uncertainty, especially when the Senate’s $15 billion transportation proposal depends on raising the state’s gas tax by 11.7 cents.

“That is the one issue that could kill the whole (transportation) package because the costs are so hard to determine,” said Rep. J.T. Wilcox, R-Yelm.

Sen. John Braun, R-Centralia, said a gas tax increase could be challenged in a referendum. Voters would be influenced by the thought they also will have to pay for more costly biofuels, he said.

“If the low-carbon fuel standard is still in play, that’s going to decisively effect that vote,” he said.

The state gas tax is currently 37.5 cents a gallon. The federal gas tax adds another 18.4 cents. Inslee has made climate change his signature issue. He’s instructed the Washington Department of Ecology to write a low-carbon fuel policy that he could enforce by executive order. To discourage Inslee from acting alone, the Senate transportation plan includes a provision that would divert transit funds to road projects if he issues an executive order.