WASHINGTON - President Donald Trump on Thursday is expected to announce an executive action as part of a renewed bid to ask about citizenship on the 2020 Census, according to two administration officials, prolonging a contentious legal and political standoff over adding the controversial question to the decennial survey.

It remains unclear exactly what Trump will announce, including whether it will be an executive order or some other action that falls short of that move. Details continued to be in flux, while advocacy groups who have challenged the citizenship question immediately threatened legal action against whatever Trump announces.

In a morning tweet, Trump said he would hold a news conference related to the census at the White House following a planned summit Thursday afternoon on social media.

"At its conclusion, we will all go to the beautiful Rose Garden for a News Conference on the Census and Citizenship," he wrote.

The White House later said his announcement will take place at 5 p.m. Trump has telegraphed since late last week that he would take some action on his own to address the citizenship question on the census, and opponents of the move said Thursday they are prepared to quickly respond.

"The Supreme Court has spoken. The Trump administration's effort to add a citizenship question to the 2020 Census is unlawful," said Dale Ho, the director of the Voting Rights Project at the American Civil Liberties Union, one of the groups fighting the question in court. "If President Trump takes executive action, we will take legal action."

House Majority Leader Steny Hoyer, D-Md., announced Thursday that the Democratic-led chamber will vote Tuesday to hold Commerce Secretary Wilbur Ross and Attorney General William Barr in contempt of Congress for not complying with subpoenas related to the administration's decision to include the citizenship question.

The White House has asserted executive privilege over the information. A House committee voted last month to approve the contempt resolution against Ross and Barr.

"I will bring that measure to the floor because the House will not shirk from its oversight of this administration and its malign effort to silence the voices of millions in our democracy and deny resources to communities in need of them," Hoyer said.

Trump's pending actions come after he abruptly reversed his administration's decision to drop the controversial question from the 2020 survey - which had come in response to a Supreme Court ruling last month that the government could not add it without a solid justification. The court called the administration's rationale for the question "contrived."

Federal officials were left scrambling last week after Trump, in a surprise tweet, overruled a decision by the Justice Department to allow the 2020 Census to proceed without the inclusion of a question that would ask residents whether they are a citizen of the United States.

But Trump has defended his approach, telling reporters at the White House last week that asking about citizenship was needed "for many reasons." He also said there is a possibility that some kind of addendum could be printed separately after further litigation.

"We'll see what happens," Trump said. "We could start the printing now and maybe do an addendum after we get a positive decision. So we're working on a lot of things, including an executive order."

At a news conference Thursday, House Speaker Nancy Pelosi, D-Calif., noted the Trump administration remains subject to injunctions barring the addition of the question.

"The president's effort to put the citizenship question on the census will continue to be challenged in court," she said.

Congressional Republicans have largely lined up behind the president, with House Minority Leader Kevin McCarthy, R-Calif., arguing Thursday that it is data the government has the right to know.

Nonetheless, the issue has produced headaches for the Justice Department, as Trump has insisted on moving forward despite earlier statements by administration officials that census forms would be printed without the change.

This week, the department sought to replace the team of lawyers assigned to the effort, after at least some career attorneys on the case grew frustrated with the Trump administration's sudden shift in position.

Two federal judges have since denied that bid.

The census fight, which once seemed at its end, intensified Wednesday when a group of conservative lawmakers wrote a letter to Barr urging him to support Trump in adding the citizenship question to the census by executive order.

The letter controversially states that assessing the citizenship question is "germane to carrying out our duty to apportion representatives."

The Trump administration has denied that adding the question is meant to boost its political fortunes through redistricting, but many Democrats charge that the question is meant to scare away Latinos from participating in the census, resulting in an undercount of that population.

This article was written by John Wager, a reporter for The Washington Post. The Washington Post's Matt Zapotosky and Felicia Sonmez contributed to this report.