Illinois lawmakers are returning to Springfield today to take up a plan to shrink Illinois’ carbon footprint and bail out its biggest utility, but the top Senate Democrat said Monday there is no deal yet on a sprawling green energy package.

In an interview with WBEZ, Senate President Don Harmon, D-Oak Park, described negotiations with Gov. JB Pritzker and other stakeholders as being about “80 to 90%” completed, but the question of mothballing two downstate coal plants remains a key sticking point.

“I would say at this point we’re doing some shuttle diplomacy, trying to figure out where there are avenues of agreement, and I’m optimistic that we are close to a landmark legislative achievement,” Harmon said. “I very much would like to see the governor standing at a podium in the next couple of days preparing to sign a bill that will transform Illinois’ energy future.”

Pritzker has demanded that the state wean itself from coal and called for a coal-powered plant in downstate Marissa that provides electricity to several Chicago suburbs to close by 2035. That mandate also would affect a coal plant that powers Illinois’ capital city, Springfield.

But Harmon and Senate Democrats are balking at shuttering the Prairie State Energy Campus. They say it would leave suburbs like Naperville, Winnetka and Geneva on the hook for long-term borrowing used to finance the power plant, which is one of the nation’s top polluters.

On Monday, Harmon floated the possibility of giving Prairie State and Springfield a lifeline by allowing the plants to stay open if they can lessen their carbon emissions, an idea that seemingly puts the Senate president at loggerheads with the governor, who has demanded the plants’ closure.

“Dirty power needs to go offline unless it can reinvent itself as something that’s much closer to clean power,” Harmon said. “I can’t guarantee they’ll do it, but I think it’s incumbent upon us to give those facilities an opportunity to make that kind of investment.”

However, when pressed, Harmon acknowledged that he does not believe the technology currently exists for Prairie State to become substantially carbon-free any time soon. Still, he said, that could change.

“I don’t know that it exists now, but 2035 is a long time away in technological terms,” he said. “It’s a short time away in climate change terms, and that’s the tension we’re trying to navigate.”

The Senate reconvenes Tuesday, and the House follows suit on Wednesday. The energy package stalled during the Memorial Day weekend when lawmakers originally had intended to finish their spring legislative session.

The energy bill Pritzker is pushing is a multi-faceted effort to reduce Illinois’ carbon emissions drastically by phasing out coal and natural gas use and encouraging electric automobile use. Part of the package pushed by Pritzker also involves a $694 million bailout for Exelon to keep three of its nuclear plants — Dresden, Byron and Braidwood — financially afloat for the next five years.

Harmon and Pritzker spoke Monday for the first time since lawmakers left Springfield earlier this month without an energy deal. Neither the Senate president nor the governor’s office would characterize Monday’s conversation, but a Pritzker aide made clear the governor was sticking by his commitments.

“As the governor has reiterated from the outset of these conversations, any clean energy package must include real and meaningful policies to address climate change,” gubernatorial spokeswoman Jordan Abudayyeh said. “Without strong and effective decarbonization provisions, the governor cannot support and sign an energy package.

“Negotiations over final details are ongoing, and the governor’s office looks forward to continuing those conversations this week as lawmakers head back to Springfield,” she said.

The Prairie State Energy Campus is represented by the lobbying firm that once employed Harmon’s chief of staff, Jacob Butcher, a relationship that has drawn scrutiny and questions about a potential conflict of interest from within some political circles at the statehouse.

But Harmon sharply defended his top aide in his first public comments on the issue and insisted Butcher’s past association “does not factor in at all” in the push by Senate Democrats to find some way to keep Prairie State from the green-energy chopping block.

“Jake Butcher left lobbying behind when he returned to public service at my request, and he works for me and he gives me good advice and I appreciate his wealth of knowledge. But his prior representations of anybody, including renewable companies, has no bearing on energy policy in the Senate Democratic caucus,” Harmon said.

And when asked about how he viewed some at the statehouse questioning Butcher being in the room as Prairie State’s future is debated, Harmon said going after legislative staffers is off-limits.

“I’m trying to bite my tongue,” Harmon said. “I would not call out the governor’s staff or the speaker’s staff for decisions or actions that the governor or the speaker take. Our caucus operates as a collection of elected representatives of the people who send us here to Springfield. We couldn’t do our jobs without an incredibly able staff. But we don’t throw staff under the bus. We’re the ones who are accountable to the people who send us here.”

Beyond the controversy surrounding Prairie State, how Commonwealth Edison ratepayers should be compensated for the company’s past lobbying transgressions also is a point still in dispute between Senate Democrats and the governor.

The Exelon subsidiary acknowledged in a settlement last summer with federal prosecutors that the company engaged in a long-running Springfield bribery scheme directed at ex-House Speaker Michael Madigan to advance its interests.

Pritzker’s legislation has called for an investigation by state utility regulators into how much ComEd’s corrupt lobbying cost ratepayers, which could be a pathway to eventual refunds for consumers. Harmon and Senate Democrats are seeking $300 million in ratepayer restitution, according to those familiar with their plan.

Harmon said restitution is an important accountability priority for Senate Democrats — along with keeping ComEd a reliable and affordable option for Illinois electricity customers.

“I hope that we can marshal the support for that,” he said of restitution. “At the same time, as angry as all of us are over the misadventure that has been portrayed in the federal pleadings, when you flip the light switch at your house, you want the lights to come on. And you don’t want your bill to go through the roof.

“So we need to invest in a reliable grid and in affordable power. That’s the goal here — even more so that the power comes from clean sources that don’t pollute our environment,” he said.

Harmon’s public statements on an energy bill came as opposition to Pritzker’s plans crystallized, though it wasn’t clear how the votes will go if it’s put up for a roll call in the House or Senate.

A 52-member coalition of mostly Republican House and Senate members Monday went on record with an open letter to the governor, warning that closing the Marissa and Springfield coal plants would harm the state.

“If Prairie State and [Springfield] are prematurely shuttered, Illinois will need to import power from other states – likely from less efficient coal plants. This would transform Illinois into a net importer of dirtier power and a net exporter of jobs,” the group said. “Instead, these plants should be viewed as a bridge to a cleaner, more stable energy future.”

Twenty other influential trade associations, including the Illinois Retail Merchants Association, Illinois Manufacturers’ Association and Illinois Chamber of Commerce, also weighed in against plans to shut the coal plants.

“The proposed energy legislation being circulated will be the largest rate hike on consumers and businesses in history,” the trade groups wrote in a letter to Pritzker.

Meanwhile, legislation that would allow for the first elected school board in Chicago history is also on this week’s legislative agenda and a House vote away from heading to the governor’s desk. Passage would be a defeat for Mayor Lori Lightfoot, who has voiced qualms about the plan.

The school board plan, which Lightfoot has opposed, would transition the city’s public school system to a fully elected board in 2027.

Under the measure, which passed the Senate, a hybrid board consisting of 11 appointees of the mayor and 10 elected by voters would begin in 2025. The election to pick the remaining board members would occur in 2026, resulting in a fully elected board by 2027.

Dave McKinney and Tony Arnold cover Illinois politics and government for WBEZ. Follow them on Twitter @davemckinney and @tonyjarnold.