WASHINGTON — President Joe Biden on Tuesday unveiled plans to enact immediate significant restrictions on migrants seeking asylum at the U.S.-Mexico border.

The long-anticipated presidential proclamation would bar migrants from being granted asylum when U.S. officials deem that the southern border is overwhelmed.

The Democratic president had contemplated unilateral action for months after the collapse of a bipartisan border security deal in Congress. Biden said he preferred more lasting action via legislation but “Republicans have left me no choice.”

Instead, he said he was acting on his own to “gain control of the border” while also insisting that “I believe immigration has always been the lifeblood of America.” Former President Donald Trump “told the Republicans … that he didn’t want to fix the issue, he wanted to use it to attack me,” Biden said.

“It was a cynical, extremely cynical, political move and a complete disservice to the American people who are looking for us not to weaponize the border but to fix it.”

Trump, on the other hand, used his social media account to assail Biden again over immigration, saying the Democrat had “totally surrendered our Southern Border” and his order was “all for show” ahead of their June 27 presidential debate.

The order will go into effect when the number of border encounters between ports of entry hits 2,500 per day, according to senior administration officials.

That means Biden’s order should go into effect immediately, because the daily averages are higher now. Average daily arrests for illegal crossings from Mexico were last below 2,500 in January 2021, the month that Biden took office.

The last time the border encounters dipped to 1,500 a day was in July 2020, at the height of the COVID-19 pandemic. The restrictions would be in effect until two weeks after the daily encounter numbers are at or below 1,500 per day between ports of entry, under a seven-day average.

Homeland Security said increased enforcement with Mexico since high-level bilateral meetings in late December has lowered illegal crossings but is “likely to be less effective over time,” creating a need for more action. “Smuggling networks are adaptable, responding to changes put in place,” the department said in a federal rule published Tuesday.

The department predicts that arrests for illegal crossings may climb to a daily average as high as 6,700 from July through September. At the border Tuesday, there were no visible signs of immediate impact.

The legal authority being invoked by Biden comes under Section 212(f ) of the Immigration and Nationality Act, which allows a president to limit entries for certain migrants if their entry is deemed “detrimental” to the national interest.

“We intend to sue,” Lee Gelernt, an attorney for the American Civil Liberties Union. “A ban on asylum is illegal, just as it was when Trump unsuccessfully tried it.”

Republicans dismissed Biden’s order as nothing more than a “political stunt” meant to show toughened immigration enforcement ahead of the election.

“He tried to convince us all for all this time that there was no way he could possibly fix the mess,” GOP House Speaker Mike Johnson said at a news conference. “Remember that he engineered it.