The Supreme Court on Tuesday vacated an earlier stay issued in the case of a conservative group fighting against a ruling that it and others like it must disclose their donors publicly.

As a result, the politically active, Karl Rove-run conservative nonprofit Crossroads GPS, and hundreds of other groups like it who’ve raised anonymous money to influence elections, will have to disclose their donors in many more circumstances.

For now, in the words of the Center for Public Integrity, “Secret money in politics will soon be a lot less secret.” The outlet noted it was unclear whether the ruling will apply retroactively to groups’ past donors.

Crossroads GPS will appeal the lower court’s ruling, but, crucially, the Supreme Court’s decision not to grant an emergency stay means a decades-old loophole allowing groups to keep donors secret has been closed, at least through the midterm elections.

“Moving forward, these groups will need to disclose to the public any donor that gave money for the purpose of influencing a federal election, regardless of whether they want to sponsor a particular race or specific communication,” election law expert Matthew Sanderson told the Washington Post. “Some groups will not need to adjust their approach to raising funds, but this will be a significant change for others.”

“In a nutshell: It limits the ability of # darkmoney groups to keep their donor lists secret this election,” the transparency-minded FEC Commissioner Ellen Weintraub wrote on Twitter Tuesday, referring to the Supreme Court’s stay denial.

“This is a real victory for transparency,” she added. “As a result, the American people will be better informed about who’s paying for the ads they’re seeing this election season.”

Chief Justice John Roberts actually had stayed the Washington, D.C. District Court’s decision on Saturday, “pending further order.” But that stay only lasted a few days until Tuesday’s court-wide stay denial, which had no dissents, BuzzFeed News’ Chris Geidner noted.

Crossroads GPS is a 501(c)(4) “social welfare” organization, one version of what are otherwise known as “dark money” groups. Such groups’ influence on elections has ballooned as a result of the Supreme Court’s 2010 Citizens United ruling.

Tuesday’s development comes as the result of a years-long lawsuit against the Federal Election Commission by Citizens for Responsibility and Ethics in Washington, the watchdog group, which argued the FEC wasn’t fully enforcing campaign finance law.

“This is a great day for transparency and democracy,” the group’s executive director, Noah Bookbinder said in a statement. “Three courts, including the Supreme Court, have now rejected Crossroads’ arguments for a stay, meaning we’re about to know a lot more about who is funding our elections.”