Sen. Elizabeth Warren (D-Mass.) on Tuesday called for an investigation into whether President Trump’s delay of emergency disaster funding for Puerto Rico violated the same law the Government Accountability Office (GAO) found the president broke by holding up funding to Ukraine.

The 2020 presidential candidate was joined by another White House hopeful, Sen. Bernie Sanders (I-Vt.), and a group of Democrats including Sens. Ed Markey (D-Mass.), Richard Blumenthal (D-Conn.) and Chris Van Hollen (D-Md.), and Reps. Alexandria Ocasio-Cortez (D-N.Y.) and Joaquín Castro (R-Texas), in a letter to the Department of Housing and Urban Development’s inspector general to call for an investigation into the delayed relief funds.

“Rather than legitimate process delays or congressionally imposed conditions, these delays, unique to Puerto Rico, seem to reflect President Trump’s personal policy preferences and biases against Puerto Rico,” they wrote.

Congress has appropriated nearly $19.9 billion in disaster funding for Puerto Rico since hurricanes Maria and Irma struck the island in September of 2017. Of that amount, only $1.5 billion has actually made it to the area, according to the Democratic lawmakers.

The inspector general’s office is already reviewing whether the White House inappropriately interfered in decisions to provide aid to Puerto Rico.

The Democratic lawmakers want the inspector general to open an additional inquiry into whether White House interference violated the Impoundment Control Act (ICA) of 1974.

The GAO issued a report at the start of the Senate impeachment trial finding that Trump violated the law by freezing nearly $400 million in military assistance funding to Ukraine, an act that spurred the House to charge the president with abusing his power.

The agency found the delay in Ukraine funding could not be attributed to a mere programmatic delay and noted the legislation does not allow the delay of congressionally appropriated funding for policy reasons.

It ruled the administration violated the same law in 2017 and 2018 related to energy and homeland security funding. In both those instances, the administration later released the funding.

Warren and her colleagues in their new letter noted the recent GAO report finding that Trump violated the law by freezing funding for Ukraine “for a policy reason” and ignored congressional appropriations.

“We are deeply concerned that the Trump administration is similarly violating the ICA by withholding emergency assistance from Puerto Rico because of the president’s ‘policy priorities,’” they wrote.

They pointed to the GAO’s legal opinion on the held-up Ukraine funding that asserted “faithful execution of the law does not permit the president to substitute his own policy priorities for those that Congress has enacted into law.”

The Impoundment Control Act provides a process for the president to request rescissions in congressionally appropriated funding. But if Congress does not act on such requests within 45 days, the law states the money “shall be made available for obligation.”

Disputed appropriations have sometimes been litigated in court, such as in Maine v. Goldschmidt, when the state of Maine won a ruling against President Carter’s attempt to hold highway funding for fiscal year 1980. The court ruled against the Carter administration that the transportation money was a “mandatory obligation.”