The Colorado Attorney General’s Office joined 24 state attorneys general in filing a formal complaint against what it called the U.S. Postal Service’s attempt to aid President Donald Trump’s efforts to seize control of elections and restrict mail-in voting.

In March, Trump signed an executive order calling for the compilation of a list of individuals in each state who are legally eligible to vote. Under the order, USPS would only be permitted to send mail ballots to individuals on the lists.

Last month, a court struck down the executive order, ruling it unconstitutional. However, according to Colorado Attorney General Phil Weiser, USPS has not withdrawn its proposed rule to implement the order.

“This is another unlawful attempt by the Trump administration to seize control of elections that are administered by the states,” said Weiser. “Colorado is a national leader in secure, accessible elections, and we won’t stand by while the federal government tries to rewrite the rules and create new barriers for eligible voters.”

In the complaint letter sent last week, the attorneys general argue the proposed rule violates the court’s order and represents an “unconstitutional federal power grab.”

The attorneys general called the proposed rule “unlawfully arbitrary and capricious,” arguing its “one size fits all” approach fails to account for the fact that each state’s voting system is tailored to its own election requirements.

The letter argued that the rule’s requirements have no logical connection to the justification offered. It said the rule is supposedly aimed at reducing fraud, yet strong evidence shows fraud is extraordinarily rare. Given that, the letter contended, there’s no reasonable link between such a narrow rationale and a proposal that would broadly reject mailed ballots that fail to meet the rule’s criteria.

Gov. Jared Polis also submitted comments opposing the proposed rule, saying it seeks to “needlessly, and illegally, insert USPS into the election process and change vote-by-mail processes in a way that could prevent eligible voters from voting.”

Colorado has mailed ballots to all eligible voters since 2013, and over 90% of voters in the state do so by mail. All ballots require the voter’s signature on the envelope, which is then verified to ensure it matches the signature on file with the state for that voter.

“We will not let Donald Trump mess with our Colorado elections,” Polis said. “With our Constitutionally-granted state power to administer elections, Colorado takes running safe and secure elections very seriously and we are grateful for our hardworking county clerks and election volunteers. Colorado, the Centennial State, is proud of our strong history of election security and voting rights.”