ATLANTA (AP) — Democratic Sen. Raphael Warnock on Friday urged Atlanta’s mayor to be more transparent in how city officials handle a petition drive led by opponents of a proposed police and firefighter training center, saying he is “closely monitoring” the issue.

Warnock’s letter comes after weeks of calls from “Stop Cop City” activists who were furious that the state’s top Democrats had stayed largely silent over the city’s plan to adopt a signature-matching verification process. Activists and prominent voting rights groups have decried the restriction as voter suppression.

“I am concerned by the past application of signature match in Georgia that likely led to discrimination and potentially the disenfranchisement of eligible voters,” Warnock wrote as he asked Mayor Andre Dickens more than a dozen specific questions, including why officials plan to use a signature-matching process and how residents can fix potential errors to prevent their petition from being tossed.

“I urge the City to err on the side of giving people the ability to express their views, including by establishing clear and transparent deadlines regarding timelines and requirements and by using any discretion available to the City under the law to accept and count all lawfully collected signatures,” the senator wrote.

A spokesperson for Dickens did not immediately comment.

The petition drive against the $90 million, 85-acre project in the South River Forest is already the subject of an ongoing court battle over whether it holds legal muster, with attorneys for the city having called the effort “futile” and “invalid.”

Activists say they’ve gathered more than 116,000 signatures from Atlanta residents, far more than the legal requirement to get a referendum on a ballot. But the campaign’s status was further muddied on Monday, when organizers carrying boxes full of signed petitions were shocked to be told that the clerk was legally barred from beginning the process of verifying the forms, saying organizers had missed an Aug. 21 deadline. The deadline had been previously extended until September by a federal judge, but an appellate court on Sept. 1 paused the enforcement of that order, throwing the effort into legal limbo.

That announcement from the city prompted a federal judge overseeing the case to accuse officials of moving the goalposts on the campaign, saying they have “directly contributed” to a widespread sense of confusion over the matter. In a statement responding to the judge, Atlanta officials denied having ever changed their stance on the petition drive and said that even though they do not believe the referendum push is valid, they “issued the petition in a gesture of goodwill and good faith.”

Dickens and others say the training facility would replace inadequate training facilities, and would help address difficulties in hiring and retaining police officers that worsened after nationwide protests against police brutality and racial injustice three years ago.

But opponents, who have been joined by activists from around the country, say they fear it will lead to greater militarization of the police and that its construction will exacerbate environmental damage in a poor, majority-Black area.