WASHINGTON >> A dozen senators are making a bipartisan appeal to President Joe Biden to reinvigorate the power of U.S. authorities to seize Iranian oil assets under an enforcement program they say has been allowed to languish.

Despite existing sanctions, Iranian oil exports jumped 35% last year and proceeds are being used to sponsor attacks on U.S. citizens and service members as well as allies, the senators said in a letter to the president.

Brinkmanship at sea was on display Thursday when masked Iranian navy commandos seized a U.S.-bound oil tanker in the Gulf of Oman, one of several vessels it has taken as bargaining chips in negotiations with the West. Without providing evidence, Tehran said the tanker had run into an Iranian vessel.

Specifically, the senators, led by Republican Joni Ernst of Iowa and Democrat Richard Blumenthal of Connecticut — both from the Armed Services Committee — complain that the Homeland Security Department’s security investigations office has been constrained in seizure operations by lack of money.

Since the enforcement program started in 2019, the office has seized nearly $228 million in Iranian crude and fuel oil linked to the Islamic Revolutionary Guard Corps, designated as a terrorist organization by the U.S., the senators said in the letter sent this past week.

But they said the office has not recently been given money that is available under the Treasury Forfeiture Fund to conduct seizures of Iranian oil.

“It is unacceptable that a U.S. government program, which makes the United States and its allies safer, provides funds to remediate the victims of terrorism, and generates income for the United States in a cost-effective manner, has been allowed to languish,” the letter says.

The push is coming from a diverse group of senators, among them Republicans Ted Cruz of Texas and Lindsey Graham of South Carolina, and Democrats Joe Manchin of West Virginia and Ron Wyden of Oregon. The White House did not immediately respond to a request for comment.