NEW YORK (AP) -- Amtrak CEO Stephen Gardner abruptly resigned from his top post at the U.S. passenger railroad this week.

Wednesday's announcement signaled that the leadership change came down to Amtrak maintaining support from U.S. President Donald Trump. In a statement, Gardner said he was stepping down "to ensure that Amtrak continues to enjoy the full faith and confidence this administration."

A successor for Gardner was not immediately named.

Gardner's departure also arrives just weeks after billionaire Elon Musk floated the idea of privatizing Amtrak, as well as the U.S. Postal Service, at a Morgan Stanley tech conference earlier this month.

Musk, who has been at the forefront of the Trump administration's aggressive push to downsize the federal government through the Department of Government Efficiency, reportedly called Amtrak "kind of embarrassing" -- while comparing the U.S. carrier to passenger rails seen in other countries, such as bullet trains in China.

When reached for comment on Thursday, the Transportation Department did not provide further details specific to Gardner's resignation. A statement from Transportation Secretary Sean Duffy took aim at Amtrak's Washington D.C. operations -- calling on Amtrak's leadership to "clean up Union Station" and "rid of our nation's treasures of homelessness and crime."

Citing unnamed sources familiar with the matter, Reuters reported Wednesday that Gardner was asked to step down at the request of Trump, who previously sought to cut Amtrak's budget in his first term.

When reached Thursday, Amtrak declined to comment on whether Gardner was asked to resign. But in Wednesday's announcement, the Amtrak board stated that it looked forward to "working with President Trump and Secretary Duffy as we build the world-class passenger rail system this country deserves."

Gardner first got his start with Amtrak as an intern back in the 90s. He later returned and worked at the rail service for the past 16 years, holding the title of CEO since January 2022.

Amtrak struggled during the height of the COVID-19 pandemic -- with the railroad seeing plummeting ridership as people across the country stopped traveling and stayed home. But passenger numbers have recently rebounded to pre-pandemic levels.

For the 2024 fiscal year, Amtrak reported an all-time ridership record of 32.8 million customer trips. That's up 15% from 2023 -- and surpasses Amtrak's previous record of 32.4 million passengers in 2019.

Ticket revenue for the 2024 fiscal year totaled $2.5 billion, a 9% jump from 2023. And Amtrak posted an adjusted operated loss of $705.2 million, also a 9% improvement year-over-year.