President Biden is expected to sign an executive order on Tuesday allowing him to temporarily seal the U.S. border with Mexico to migrants when crossings surge, a move that would suspend longtime protections for asylum seekers in the United States.

Mr. Biden’s senior aides have briefed members of Congress in recent days on the forthcoming action and told them to expect the president to sign the order alongside mayors from South Texas, according to several people familiar with the plans.

“I’ve been briefed on the pending executive order,” said Representative Henry Cuellar, Democrat of Texas who previously criticized Mr. Biden for not bolstering enforcement at the border earlier in his presidency. “I certainly support it because I’ve been advocating for these measures for years. While the order is yet to be released, I am supportive of the details provided to me thus far.”

The order would represent the single most restrictive border policy instituted by Mr. Biden, or any modern Democrat, and echoes a 2018 effort by President Donald J. Trump to block migration that was assailed by Democrats and blocked by federal courts.

Although the executive action is almost certain to face legal challenges, Mr. Biden is under intense political pressure to address illegal migration, a top concern of voters ahead of the presidential election this year.

The decision shows how the politics of immigration have tilted sharply to the right over the course of Mr. Biden’s presidency. Polls suggest growing support, even inside the president’s party, for border measures that once Democrats denounced and Mr. Trump championed.