— House and Senate negotiators are pointing fingers at each other after failing to reach agreement on a bill setting out requirements for how and when Duke Energy would clean up 33 coal ash ponds at 14 locations around the state.

Should the impasse continue, it would delay, but not kill the measure.

Time was running out on the current legislative session Thursday as Rep. Chuck McGrady, R-Henderson, the lead negotiator in the House, left after a day of floor debate and negotiations saying that there was an "impasse" over the bill.

Senators plan to adjourn in the early hours of Friday morning, meaning that, unless a deal is reached sometime before midnight, any measure would likely have to wait until later this month or potentially until November.

"I don't want to debate the Senate through the press," McGrady said, declining to enumerate the sticking points and saying only that the two sides were at loggerheads.

Coal ash came to the forefront of North Carolina's public policy debate on Feb. 2, when a spill in Rockingham County dumped 40,000 tons of the toxin-laced goop into the Dan River. Coal ash is the material leftover after coal is burned for fuel and contains mercury, arsenic and other poisons.

"We are working on it," Senate President Pro Tem Phil Berger said earlier Thursday when asked about progress on the measure.

In fact, senators said they believed they had a deal Thursday, and their negotiators signed a conference report, which is the formal document that usually bridges the gap between two sides.

Sen. Mike Woodard, D-Durham, expressed "real disappointment" on his Facebook page.

"There will be no time to complete this bill before adjournment," Woodard posted Thursday afternoon. "We had time to take action...but leadership frittered the time away."

Senate negotiators said House negotiators refused to sign the report. But Rep. Ruth Samuelson, R-Mecklenburg, another House negotiator, said her team had never even seen the Senate's document.

"We did not refuse to sign it," she emphatically told reporters Thursday evening.

Samuelson said the impasse was over one issue: how or whether to define "low-risk" coal ash ponds, the last ones the bill would require the utility to close and remediate.

Neither the House nor the Senate version originally included such a definition, but Samuelson said House members felt it was important to add it.

Senate Rules Committee Chairman Tom Apodaca, R-Henderson, told reporters earlier Thursday the talks were stymied by the House's insistence on adding "new language."

Another key difference between House and Senate versions of the bill involved the oversight of coal ash cleanup. The House bill would have left much of the supervision in the hands of the Department of Environment and Natural Resources, while the Senate would empower an independent board to supervise the cleanup. The Senate also called for more stringent cleanup timelines.

Lawmakers are scheduled to adjourn their summer session this week. Senators plan to leave before sunrise Friday, while House members will leave town sometime on Saturday. A proposed adjournment resolution would allow the legislature to consider coal ash during a special one-day session in August or a planned November session that will primarily focus on Medicaid reform.