President Donald Trump waves Sunday as he walks on the South Lawn after stepping off Marine One at the White House in Washington. Credit: Alex Brandon | AP

President Donald Trump on Monday offered his endorsement to a growing movement to adopt daylight saving time year-round, ending the century-old practice of semiannual clock adjustments in the United States.

“Making Daylight Saving Time permanent is O.K. with me!” Trump said on Twitter.

His tweet followed the introduction of a bill last week by Sen. Marco Rubio, R-Florida, that would make daylight saving time a year-round reality. Another Florida Republican, Rep. Vern Buchanan, introduced matching legislation of the Sunshine Protection Act in the House.

Several state-level initiatives have also been launched, including in Florida, where last year lawmakers signaled their intent to go year-round with daylight saving time.

On Saturday, a similar bill passed in the Washington state House and is awaiting action in its Senate.

Under federal law, states are only empowered to opt out of daylight saving time and remain on standard time year-round.

Daylight saving time was implemented haphazardly for decades, until Congress passed the Uniform Time Act in 1966 to bring some order to the system.

Congress has extended the duration of daylight saving time twice, and it now covers two-thirds of the year. Since 2007, daylight saving time has begun on the second Sunday in March and ended on the first Sunday in November.