Sen. Tom Cotton, R-Ark., is renewing his opposition to permanent daylight saving time, warning the latest House-passed proposal would leave millions of Americans facing dangerously dark winter mornings.

The senator on Wednesday shared a graphic on X showing that under year-round daylight saving time, the sun would not rise until after 9 a.m. in parts of many states — and as late as 11:13 a.m. in Anchorage, Alaska.

The map highlighted projected latest winter sunrises in cities across the country, including 9:46 a.m. in Williston, North Dakota; 9:29 a.m. in Kalispell, Montana; 9:20 a.m. in Pierre, South Dakota; 9:14 a.m. in South Bend, Indiana; and 9:10 a.m. in North Platte, Nebraska.

Cotton has argued the delayed daylight would create unnecessary safety risks for schoolchildren and morning commuters.

The renewed push comes after the House approved the Sunshine Protection Act by a bipartisan 308-117 vote.

The legislation would make daylight saving time permanent nationwide while allowing states to opt out by remaining on standard time before the law takes effect.

President Donald Trump has backed ending the twice-yearly clock changes, saying Americans are tired of resetting their clocks every spring and fall.

But the measure again faces a major obstacle in the Senate, where Cotton has emerged as one of its most determined opponents.

According to the Washington Examiner, Cotton has said he regrets not personally blocking a similar bill in 2022, when it unexpectedly passed the Senate by unanimous consent before later stalling in the House.

The senator has vowed not to let that happen again.

Cotton argues that permanent daylight saving time would force children to head to school before sunrise during the winter months while increasing risks for commuters traveling in darkness.

His position echoes concerns raised by sleep researchers and medical organizations, including the American Academy of Sleep Medicine, which has generally endorsed permanent standard time because it better aligns with the body's natural circadian rhythms.

Supporters of permanent daylight saving time counter that longer evening daylight encourages outdoor recreation, boosts retail activity, and eliminates the inconvenience of changing clocks twice each year.

The debate also revives memories of Congress' experiment with year-round daylight saving time during the 1973 energy crisis.

The policy quickly became unpopular after winter sunrises slipped well past 8 a.m. in many parts of the country, prompting Congress to repeal it in 1974.

With Cotton signaling he will again oppose the measure, supporters may face another difficult path in the Senate despite broad bipartisan support in the House and continued backing from Trump.