President Joe Biden’s nominee to the World Trade Organization said she will work to “restore” the institution’s defunct appellate body, which previously had the final say in trade disputes that affected billions of dollars in international commerce.

“I suspect I will spend a lot of time having these conversations with our counterparts at the WTO to make sure we can restore the appellate body and the system to the way that we envisioned at the beginning,” Maria Pagan said during a Senate Finance Committee hearing on Tuesday. “I don’t think it’s going to be an easy conversation.”

“We never intended for the appellate body to be a rule-making body,” Pagan told lawmakers. “We believe that rules have to be enforced but it has to be the rules as they were negotiated and agreed by the members.”

The Trump administration paralyzed the WTO appellate body in December 2019 when it blocked all new appointments to the seven-member panel, saying it had overstepped its mandate.

The Biden administration has maintained its predecessor’s hold on appellate-body nominations, saying that the U.S. “continues to have systemic concerns” with the functioning of the panel.

Pagan said that if confirmed, she would try to secure a waiver to the WTO’s intellectual-property rules for Covid-19 vaccines. “We have been working and will continue to work on securing a successful outcome,” Pagan said.

Though the U.S. announced it support for an IP waiver for vaccines, WTO members continue to disagree about the fundamental question of whether it’s the appropriate and most effective way to address the shortage of vaccines.

That split could sink prospects for an ambitious vaccine waiver because WTO decisions must be taken on the basis of consensus—which means any of the 164 members can veto a final agreement for any reason.