WASHINGTON – A federal district judge Tuesday struck down the Trump administration’s plan to add a question on citizenship to the 2020 Census, ruling that Commerce Secretary Wilbur Ross exceeded his authority under federal law.

The much-awaited decision by Judge Jesse Furman is likely to wind up at the Supreme Court, which next month is scheduled to consider a portion of the case – whether Ross can be required to give a deposition about the reasons for his decision. But Furman’s ruling temporarily makes that question moot.

Ross announced the addition of the citizenship question last March, but it has been tied up by a half dozen lawsuits. The government has not asked about individuals' citizenship on the Census since 1950.

Opponents, including California, New York, the American Civil Liberties Union and immigration rights groups, contend fears of deportation among undocumented immigrants will cause them to be undercounted.

In his 277-page ruling, Judge Furman discounted Ross's contention that he made his decision based on the Justice Department's request. Instead, Furman said, Ross opted for the citizenship question for other reasons and then tried to conceal his motives by getting the Justice Department to ask for it.

"The court can – and, in light of all the evidence in the record, does – infer from the various ways in which Secretary Ross and his aides acted like people with something to hide that they did have something to hide," Furman said.

Opponents of the citizenship question allege that Ross made his decision after conversations with White House officials, including former chief strategist Steve Bannon, as well as former Attorney General Jeff Sessions.

“The court’s finding that the administration concealed its true motives further attests to its hostile intentions,” said Marc Morial, president of the National Urban League.

Dale Ho, director of the ACLU’s Voting Rights Project, welcomed Furman's decision, calling it "a forceful rebuke of the Trump administration’s attempt to weaponize the Census for an attack on immigrant communities."

"The evidence at trial, including from the government's own witness, exposed how adding a citizenship question would wreck the once-in-a-decade count of the nation's population," Ho said. "The inevitable result would have been – and the administration’s clear intent was – to strip federal resources and political representation from those needing it most.”

Furman's ruling is sure to be appealed, most likely to the Supreme Court, unless the administration drops the issue. That did not seem likely Tuesday.

“Our government is legally entitled to include a citizenship question on the Census, and people in the United States have a legal obligation to answer," Justice Department spokeswoman Kelly Laco said. "Reinstating the citizenship question ultimately protects the right to vote and helps ensure free and fair elections for all Americans.”

The ultimate court decision could affect the political and financial clout of immigrant communities for the next decade. What's at stake is an accurate count of immigrants in the Census, including the more than 22 million noncitizens. Challengers fear a citizenship question could prompt many to avoid being counted.

That, in turn, could cause parts of the country with large percentages of immigrants – mostly in states dominated by Democrats – to be undercounted, which in turn could result in a loss of federal funds and, potentially, seats in Congress.

The Supreme Court previously refused the Trump administration's request to delay the district court trial. It gave both sides a partial victory when it ruled that Ross did not have to give a deposition concerning his decision-making process before the trial, but other federal officials could be questioned out of court.

Now the question will be whether the high court delays or cancels its Feb. 19 oral argument on whether Ross can be deposed to assess his motives. The court could decide instead to hear the full case on the citizenship question this spring, since preparations for the Census are scheduled to begin this summer.

More:President Trump bets big on Supreme Court to uphold controversial policies after lower court losses

More:Supreme Court turns down Trump request to restart asylum ban

More:Federal appeals court rules against Trump administration effort to end DACA program