Democratic Congresswoman Ayanna Pressley, a member of the House Financial Services Committee, sent Treasury Secretary Steve Mnuchin a letter Thursday challenging the former Wall Street executive to explain his recent decision to postpone the planned 2020 redesign of the $20 bill to feature the abolitionist Harriet Tubman.

In testimony before the committee last month, Mnuchin announced that his department would forgo placing Tubman on the $20 bill—a plan developed over a ten-month-long public comment and review period by former Treasury Secretary Jack Lew—and instead focus on implementing security features for the 2020 deadline.

“Please provide specific detail about your Agency’s decision and rationale to postpone the release and circulation of the $20 redesign,” the letter to Mnuchin’s office reads.

In his exchange with Pressley at last month’s hearing, Mnuchin was relatively opaque about the exact decision-making process that led Treasury to modify Lew’s original plan, which would have coincided with the 100th anniversary of the ratification of the 19th amendment, which granted women suffrage nationwide.

“The primary reason we have looked at redesigning the currency is for counterfeiting issues,” Mnuchin explained to Pressley at the time. “Based upon this, the $20 bill will now not come out until 2028.”

Pressley’s letter on Thursday pressed for transparency about the redesign for all U.S. bank notes, requesting a “specific timeline” for all current redesign plans. As part of her efforts to probe the rationale behind the postponement, the congresswoman is seeking answers from Mnuchin about the specific date the decision was made, the recorded reasoning behind it and any internal communication about the plans.

Pressley is also looking into the removal of a Treasury Department website which was devoted to the redesign campaign. That URL now directs to the Bureau of Engraving and Printing.

It is not an entirely surprising development that the Tubman redesign would run into obstacles under the Trump administration.

Andrew Jackson, one of Trump’s favorite presidents, would have been unseated by Tubman under Lew’s original plan and consigned to a less prominent spot on the back of the bill.

During the 2016 campaign for president, Trump said the redesign announcement was “pure political correctness” and suggested a better place for Tubman might have been the rarely printed $2 bill.

“Andrew Jackson had a great history, and I think it’s very rough when you take somebody off the bill,” he said on the campaign trail. “Andrew Jackson had a history of tremendous success for the country.”

He added, though, that he thought Tubman was “fantastic.”

The New York Times has reported that some senior Treasury officials believe the postponement was an attempt to appease President Trump’s disdain for the decision enough to prevent him from scrapping it altogether.

In a statement to Newsweek, Pressley expressed her frustration in trying to determine a reasonable explanation for the change of course.

“No one in this Administration is doing their job,” she said. “They continue to stonewall, to obstruct, and to ignore the will of the American people. Our diversity is our greatest strength and the American people understand the importance of representation.”