Biden's top economic adviser, Brian Deese, and Labor Secretary Marty Walsh, who were involved in earlier negotiations preventing a nationwide rail shutdown, held a series of calls with executives from CSX, Union Pacific, Berkshire Hathaway's BNSF and Norfolk Southern in recent days, a White House official said.

They "pressed the railroad operators to make progress," the official said, without offering details. The calls were made to check in on the progress made so far and remind the railroads the White House expects the companies will do more for their workers, a second White House official said.

CSX announced on Tuesday that it had reached a deal with two railroad unions regarding paid sick leave, the sticking point in last year's contract dispute between 12 rail unions and U.S. freight railroads.

The deal is a "good step" and in part a result of continued engagement from the administration, the second White House official said. CSX did not immediately respond to a request for comment.

CSX has said it will continue to pursue agreements with the remaining 10 unions. Union Pacific, BNSF and Norfolk Southern do not currently offer workers paid sick leave.

On Dec. 2, Biden signed legislation to block a railroad strike that could have wrecked the nation's economy, upsetting unions that had been negotiating for months. At the time, Biden pledged to secure paid sick leave for American workers "before it's all over."

Railroads have slashed labor and other costs to bolster profits in recent years, and have been fiercely opposed to adding paid sick time that would require them to hire more staff.

After Biden signed the bill in December, rail unions said they are discussing an executive action with the White House on paid sick time.

Celeste Drake, deputy director of the White House's National Economic Council, told Reuters in a statement the administration has continued to evaluate "all legislative and administrative options" on the issue.

(Reporting by Nandita Bose in Washington; Editing by Heather Timmons and Leslie Adler)

By Nandita Bose