FILE PHOTO: U.S. President Donald Trump speaks during an event honoring 2018 NASCAR Cup Series Champion Joey Logano at the White House in Washington, U.S., April 30, 2019. REUTERS/Joshua Roberts

WASHINGTON (Reuters) - A Republican U.S. senator on Wednesday said President Donald Trump will not waive rules requiring that only U.S.-flagged ships move natural gas from American ports to Puerto Rico and the U.S. Northeast.

The nearly 100-year-old Jones Act mandates the use of U.S.-flagged vessels to transport merchandise between U.S. coasts. Republican senators said the administration was seriously considering waiving the requirements for 10 years. Bloomberg News reported last week that Trump was leaning in favor of some kind of waiver.

Senator Bill Cassidy, a Louisiana Republican, told reporters on a conference call that Trump told Republican lawmakers he would not support a waiver. The White House did not immediately comment.

Cassidy said Trump told them “he was going to oppose any changes to the Jones Act and any waivers. That’s what we went there hoping to get and that’s what we did get.” He added that Trump gave his word to lawmakers, which included Republicans from Alaska and Mississippi as well.

A person briefed on the matter told Reuters Tuesday that administration officials were divided on the issue.

Senator John Kennedy, another Louisiana Republican, said in a statement the Jones Act supports 71,000 jobs in the state. “After talking to President Trump, I am confident that he realizes how important the Jones Act is to Louisiana’s maritime industry and that no changes will be made,” Kennedy said. “It would be foolish to push aside those jobs in favor of foreign-made and foreign-crewed ships.”

In 2017, the Department of Homeland Security waived the requirement for one week to allow oil and gas operators to use often cheaper, tax-free, or more readily available foreign-flagged vessels to ensure enough fuel reached emergency responders during Hurricane Irma and following Hurricane Harvey.

In February, leaders of the House of Representatives Committee on Transportation and Infrastructure wrote to the DHS to oppose a request from Puerto Rico to waive the Jones Act for 10 years to allow foreign tankers to move liquid natural gas to the U.S. island territory.