The Democratic and Republican leaders of the Vermont House said Wednesday that a pitched debate over new development rules for rural land has led to a rise in “hateful” and “demonizing” messages targeting state legislators.

“These personal, threatening attacks are unacceptable anywhere, and especially in Vermont, where we have a long history of civil debate and respectful dialogue,” wrote House Speaker Jill Krowinski, a Democrat, and House Minority Leader Pattie McCoy, a Republican.

The unusual joint statement comes as legislators work to unravel a two-year-old law that would subject development near ecologically sensitive areas — as well as some new roads and driveways — to greater regulatory scrutiny. Opposition to the law, known as Act 181, has grown into what some have described as a rural rebellion, with potential electoral ramifications this fall.

Krowinski and McCoy wrote that it was healthy and important to debate the law, and that legislators had listened: The House and Senate recently voted to remove the most controversial provisions from Act 181, and Gov. Phil Scott, a Republican, is expected to sign those changes into law.

But the leaders said that some had taken the debate too far and targeted an architect of the law, Representative Amy Sheldon, with “truly reprehensible” emails and social media posts.

Conor Kennedy, Krowinski’s chief of staff, provided an array of screenshots showing people calling Sheldon, the Democratic chair of the House Environment Committee, a Nazi, a dictator, a “retarded meatpuppet” and more.

“Step on my grass and one of us will die,” one self-described Vermonter wrote.

According to Kennedy, each of the comments originated with a 15,000-member Facebook group known as Rural Vermont Rising, which has served as a key organizing tool for the anti-Act 181 movement.

Colleen Geddis, who created the group, said Wednesday that she and her fellow moderators had banned personal attacks and harassment from the page and sought to root out and remove offending comments.

“We try to police it, but there’s only so much you can do on social media,” she said. “It’s not the way to get things done, and we know that.”

Political debate in Vermont tends to be more civil than elsewhere, perhaps due to its small size, tradition of local governance and citizen legislature. But certain subjects have led to overheated rhetoric in recent decades, including debates over civil unions in 2000 and gun rights in 2018.

Sheldon, who was first elected to the House in 2014, said she had never witnessed as much vitriol as with the debate over Act 181. Though she steers clear of social media, she said, she had received “veiled threats” and, at times, felt physically unsafe.

“I get that land use laws touch on property rights, and that’s a thorny issue,” she said. “I think we responded to legitimate pushback, but it’s not stopping. It’s like, ‘We met you halfway,’ and it’s unrelenting.”

Paul Heintz can be reached at paul.heintz@globe.com. Follow him on X @paulheintz.