SENATE PRESIDENT STAN ROSENBERG said on Wednesday that the state Senate will work to fashion a compromise bill on charter schools in an effort to stave off a costly and divisive ballot question campaign this fall.

Rosenberg, who had previously sounded pessimistic about the prospects of the Senate taking up the issue, told reporters this afternoon that a working group of four Democratic senators will begin meeting to try to come up with a bill. “There is no guarantee of the outcome, but people of good will can often find a path forward,” Rosenberg said, flanked by a group of Democratic senators.

The Senate killed a charter school bill in 2014, setting in motion efforts by charter proponents to bring the issue to the ballot this fall.

Gov. Charlie Baker, a big charter supporter, has also filed legislation to allow more charter schools.

The Globe reported earlier this month that a business-backed coalition is prepared to spend as much as $18 million on the ballot question, which would allow up to 12 new charter schools per year.

Opponents, including the Massachusetts Teachers Association, have promised to vigorously fight the ballot measure.

Rosenberg said a starting point for the Senate discussion would be reform to various charter school practices, including their approach to retaining students and policies on what to do with empty seats when students leave a charter school. Critics have said it is unfair for some charters to leave seats unfilled when students leave and to only admit students at the start of the school year, since district schools must enroll students whenever they arrive in a community.

“We’re starting with a conversation about reform, not with how many more charters,” he said. “We want the best practices that are being done in the best of the charters to be done by all charters.”

Rosenberg said the contentious issue of charter school funding would also be on the table. “That’s one of the biggest complaints that people have,” he said, referring to the current funding system, in which per pupil funding follows students. It’s not clear what an alternative funding scheme might look like.

The House passed legislation to raise the charter cap last session, but the measure was defeated in the Senate by a wide margin, 30-9.

Sen. Linda Dorcena Forry of Dorchester, one of the nine senators to support the charter bill, said she wants to see the cap raised. But in what may be an indication of how far charter advocates will need to compromise to win passage of a bill in the Senate, she sounded more like a charter critic as she stood alongside Rosenberg this afternoon.

Forry said reforms are needed to address the practice of charter schools that “counsel students out,” and she decried the practice of then leaving seats vacant. “I think that’s a big piece of reform we’ve got to talk about,” she said. “It’s unacceptable.”

Charter supporters welcomed today’s development, but seemed to caution against any compromise that doesn’t include a meaningful increase in charter capacity.

“While it is encouraging to hear the Senate president will move ahead with legislation on charter schools, any bill that comes out of the legislature must address the needs of the 37,000 families stuck on waiting lists to attend a public charter school,” Eileen O’Connor, spokeswoman for Great Schools Massachusetts, the group behind the ballot campaign, said in a statement.

“We’re very encouraged that the Senate is going to weigh in on this and we look forward to engaging them in discussion,” said Marc Kenen, executive director of Massachusetts Public Charter School Association, who was walking into the State House just after Rosenberg met with reporters. “We’re going into this with an open mind and hope that there can be a compromise agreement.”

Baker joined with charter school supporters at the State House on Tuesday as they delivered petitions with more than 25,000 signatures calling on the Legislature to raise the charter school cap.

“Gov. Baker strongly supports lifting the cap on public charter schools, whether through legislative action or ballot initiative, as a way to give parents and students in underperforming districts access to the high quality education they deserve,” said Billy Pitman, Baker’s deputy communications director, in a statement.

The working group in the Senate will be made up of Senate Ways and Means chairwoman Karen Spilka, Sen. Sonia Chang-Diaz, the Senate chairwoman of the Legislature’s Joint Committee on Education, Sen. Patricia Jehlen, the education committee’s Senate vice chair, and Sen. Dan Wolf, whose two daughters attended charter schools on Cape Cod and who served for several years on the board of one of the schools.

Rosenberg said the working group would “move expeditiously” to put a bill before the Senate.

The charter debate follows a long history of advocates using the threat of a ballot question to force the Legislature to take up an issue.

Health care policy expert – and one-time state lawmaker — John McDonough wrote in the current issue of CommonWealth about a similar debate unfolding on Beacon Hill being driven by a question set to appear on the November ballot to regulate hospital prices.

“If the ballot question didn’t exist, this debate would not occur,” Rosenberg said of the charter school issue the Senate will now consider. “There’s no question about it.”

“I’ve been involved in three efforts in the past to deal with ballot questions, and we’ve found common ground and had very successful processes,” he said. “I don’t guarantee any outcome here other than the best effort to come up with the best bill we can put on the floor and debate.”