Billionaire climate activist warned Republican lawmakers not to block President Obama's replacement for Supreme Court Justice Antonin Scalia who died last weekend.

"The confirmation of a new Supreme Court justice is one of the key battles right now in the fight to address climate change," Steyer said in a statement Wednesday. "Last week's stay of the Clean Power Plan made clear just how much power the court has in determining our country's clean energy future."

The 5-4 decision by the Supreme Court on Feb. 9 put a halt on the climate rule until all litigation concludes in the D.C. Circuit Court of Appeals, as well as expected follow-up suits in the high court. Many believe the court action will extend well beyond Obama's presidency, making the climate rule void until then.

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Steyer says he is confident the president's pick as Supreme Court justice will not obstruct the administration's far-reaching climate rules.

"President Obama is right to fulfill his constitutional duty to nominate the next Supreme Court justice, and I'm confident that his nominee will be a strong defender of the progress our country has made in tackling the climate crisis," Steyer added. He said his advocacy group NextGen Climate "is fully committed to holding accountable politicians who stand in the way of progress and our country's efforts to build a healthier, more sustainable economy for our kids."

The last vote Scalia gave before dying on Saturday was to halt the centerpiece of President Obama's climate agenda, the Clean Power Plan. Scalia, with his four conservative colleagues, agreed to stay the plan in accordance with 29 states' motion to halt the regulations until the D.C. Circuit Court of Appeals rules on the merits of their arguments later this year.

"Many West Virginians should be proud of the legacy of the Justice Scalia because his decision has given a monumental victory to the state — one of the single most important wins for the state of West Virginia in decades," said West Virginia Attorney General Patrick Morrisey, who is leading the 29 states. Former Environmental Protection Agency air office chief Jeff Holmstead, now a partner at law firm Bracewell Giuliani, told the Washington Examiner that the stay will hold despite Scalia's death. "It will not affect the stay," he said in an email to the Washington Examiner. "The stay will remain in place until the Supreme Court disposes of the case — either by denying [petition for review] or, more likely, but passing judgment on the rule itself."

The Supreme Court is expected to take up the D.C. Circuit decision on the Clean Power Plan, whether it rules in favor or against it.

"I know the rule's supporters think their chance are better without Scalia, and this may be true, but I still think the rule is pretty vulnerable," Holmstead said. "EPA has gone so far beyond the language of the statute and the intent of Congress that the Democratic appointees may have a hard time upholding the [Clean Power Plan]. The fact that they voted against the stay doesn't mean that they will vote to uphold the rule."

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The states will begin filing briefs in the appeals court at the end of the week. Oral arguments are scheduled for June.