The Supreme Court has denied a request from a conservative political group to temporarily block a lower court ruling which would force it to disclose its donors.

The request for a stay had initially been entered by Chief Justice John Roberts on Saturday after Karl Rove's Crossroads GPS disputed an earlier ruling that invalidated a Federal Election Commission regulation allowing donors to remain anonymous.

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In the order Tuesday, which was issued by Roberts, the court refused to further delay the U.S. District Court for the District of Columbia's decision to invalidate the regulation. That ruling was made in August by Judge Beryl A. Howell.

The original decision, in a case brought by Citizens for Responsibility and Ethics in Washington (CREW), required that so-called dark-money groups that spend at least $250 in independent expenditures report every contributor who gave at least $200 in the past year.

A report earlier this month revealed that large dark-money groups contribute an outsized amount of money to elections.