WASHINGTON, Sept 9 (Reuters) - The Illinois legislature on Thursday edged closer to approving a deal that would save two Exelon Corp nuclear power plants from closing beginning on Monday after the House speaker announced his support for a deal added to a state energy bill.

House Speaker Emanuel "Chris" Welch, a Democrat, said the amendment "prioritizes our climate, equitable job preservation and creation and ethics reform."

The amendment, which was also supported by environmental and labor groups, requires coal plants including Prairie State, the state's largest carbon emitter, to cut current emissions 45% by 2035 and to be 100% carbon free, or close, by Dec. 31, 2045. The plants can use any technology including the burning of hydrogen produced by renewable power to meet those levels.

Exelon has said it will close its Byron nuclear plant on Sept. 13 and Dresden in November if a state or federal program does not come to the rescue. U.S. nuclear plants have been struggling to compete with wind and solar farms and plants that burn low-cost natural gas.

The amendment was added to wider energy legislation containing nearly $700 million in carbon mitigation credits over five years for three Exelon nuclear plants, including the Braidwood facility, which the company has said is at risk but has not scheduled a date to close.

Welch said in statement he hopes to see the "same broad bipartisan support in the House for this historic piece of legislation" that the amendment generated among advocacy groups. It was uncertain if the House and Senate, which both have Democratic majorities, would approve the wider legislation.

Illinois Governor J.B. Pritzker, a Democrat, has said he would sign the legislation if it reaches his desk.

Preventing nuclear plants from closing has been a priority for the administration of President Joe Biden which sees many of the plants as important to its goal of decarbonizing the power grid by 2035.

(Reporting by Timothy Gardner; Editing by Nick Zieminski)