In normal times an American president simply can’t tell the U.S. Postal Service what kind of contract to sign with a customer like Amazon. He has zero authority to do so.

These are not normal times.

In a nearly weeklong assault on Amazon, President Trump has bashed the online giant’s package-shipping deal with the postal service. He insists the post office is losing money hand over fist and that Amazon AMZN, +5.69% should pay more, despite no evidence to back up his claim.

Can the president make Amazon fork over more money? No, not directly.

Read:Amazon not likely to pay higher Postal Service rates despite Trump attacks

By law the USPS operates independently. The service is led by a postmaster general and a deputy who in turn are selected by a bipartisan board of nine governors.

Board members are chosen by the president and confirmed by the Senate. No more than five members can belong to one political party.

Right now all nine seats are empty. The last one to leave was James Bilbray, who turned out the boardroom lights in 2015.

That leaves two people running the USPS: Postmaster General Megan Brennan, the first women to head the service, and Deputy Postmaster General Ronald Stroman.

Aside from picking the postmaster general, the board makes long-range plans, review operations and offer advice on how to better run the USPS.

Read:Trump’s attacks on Amazon break with history of presidents keeping hands off

The last time the board had nine members was in 2010. After much delay President Obama offered a slate of nominees in his second term, but they were blocked by Democratic and Republican opposition. Sen. Bernie Sanders, for instance, objected to USPS plans to close some rural branches in states such as Vermont.

“The postal service is not a priority for anyone on Capitol Hill,” said James Gattuso, a regulatory analyst at the conservative-leaning Heritage Foundation. “The USPS is low on the list when you have thousands of appointments to fill.”

Technically Trump could shape future USPS deals with Amazon through his choice of board nominees. Even if he tried to, his picks would require confirmation by a closely divided Senate that has been very slow to approve any of his appointees. Trump would be required to nominate up to four Democrats.

Trump nominated three people to serve on the USPS board in October, but the Senate hasn’t acted on them and has no immediate plans to do so.

Trump’s intervention is unlikely to help the cause, either. Senators may balk at a slate of nominees if they shifted the makeup of USPS leadership to reflect a clearly pro-Trump agenda.

“Obviously Trump could have an influence, but the board has not usually been partisan,” said Gattuso. “The last thing you need is a political dimension in which the president or Congress says, ‘do this’ or ‘don’t do this.’”

The pressure brought to bear on the USPS, however, could spur its postmaster general to seek better terms when the current contract with Amazon expires. USPS declined to comment on any details about its contract with Amazon, including when it expires.