WASHINGTON – The first subpoenas from House Democrats to Attorney General William Barr may be authorized Tuesday, and they won't have anything to do with special counsel Robert Mueller's report on Russian interference in the 2016 election.

The House Committee on Oversight and Reform is scheduled to vote on issuing subpoenas for documents and testimony relating to its investigation into the addition of a question on citizenship to the 2020 census.

Committee Chairman Elijah Cummings' requests dovetail with legal challenges to the question, which critics contend is aimed at suppressing the official count of non-citizens in the census. Two federal judges have blocked the question from being added, and the Supreme Court will hear the case later this month.

Here are the details on the simmering controversy:

2020 census and citizenship

The count of the nation’s population begins April 1, 2020. The decennial survey is key to apportioning congressional districts and determining the distribution of federal funds to schools, health systems, highway projects and other programs. The information helps determine the annual distribution of $675 billion in federal funds.

Census Bureau officials held a press conference Monday to outline the bureau’s preparations, including a national ad campaign and partnerships with grassroots groups to reach people, particularly communities of color.

The Commerce Department announced one year ago that it would ask every household about citizenship for the first time since 1950. Other decennial censuses have asked about citizenship only on the "long form," which goes to 1 in 6 households. The last time was for the 2000 census.

More:Census officials await Supreme Court decision on whether to add, drop citizenship question

The question also has been asked since then as part of the Census Bureau's American Community Survey, but that polls only a fraction of U.S. households. The administration's justification was that the question is needed to count minorities accurately, so that their rights can be protected.

Challenges to the question

A wide range of critics, including the American Civil Liberties Union and the states of California and New York, charged that adding the question was nothing more than an attempt to intimidate non-citizens from participating in the census. That could cause them to be undercounted, possibly resulting in the loss of federal funds and congressional representation.

The challengers alleged a political motive with roots in the White House, noting that Ross had consulted with Steve Bannon, President Donald Trump's chief strategist at the start of his administration.

During a hearing last month, Cummings cited discussions between Ross and Bannon as early as July 2017, months before the Justice Department formally asked to include the citizenship question. He said Ross also discussed the matter with Kris Kobach, who led Trump's short-lived presidential commission on voter fraud.

Ross has said all along that the decision had nothing to do with politics. He told the committee that the Bannon and Kobach talks came early in his tenure as Commerce secretary, while he was learning about the census and conducting research on the citizenship issue.

"I wanted to make sure that we had enough time to adequately consider any formal request that DOJ might make," he told the House committee in March.

The trials on the question

In January, U.S. District Court Judge Jesse Furman in New York ruled that Ross exceeded his authority by adding the citizenship question.

In a 277-page ruling, Furman called Ross's contention that he based his decision on a Justice Department request a "sham justification." He said Ross made his decision for other reasons, then tried to conceal his motives by getting the Justice Department to make the request.

"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.

In March, U.S. District Judge Richard Seeborg in Calilfornia also struck down the question, ruling that its inclusion would lead to such drastic population undercounts that it "threatens the very foundation of our democratic system."

In his 126-page decision, Seeborg said the trial record indicated that Ross called for the citizenship question after consulting with Bannon, Kobach and others.

"Secretary Ross does not wish his reason for requesting the inclusion of the citizenship question on the 2020 census to come to light," the judge concluded.

The House committee's involvement

Frustrated by Ross's refusal to answer some questions last month, Cummings is seeking to subpoena in particular a memorandum and note from Commerce Department counsel James Uthmeier to John Gore, the acting assistant attorney general for civil rights in the Justice Department. He also is demanding Gore's appearance before the panel.

In addition, Cummings is seeking "all documents and communications" relating to the citizenship question for most of 2017, both within the Justice Department and with outside entities, including the White House, the Trump presidential campaign and the Republican National Committee.

The agency said in a statement Monday it "has cooperated in good faith with the committee and will look to do so in the future.”

“The Department has delivered over 11,000 pages of documents pertaining to the Committee’s request and the Secretary himself voluntarily testified for nearly seven hours on these issues two weeks ago,'' said an agency spokesman.

Now what?

The Supreme Court granted the Trump administration's request to hear the case, now scheduled for oral argument April 23.

The justices previously had ruled that Ross could not be questioned by lawyers for those seeking to block the citizenship question, but that Gore could be questioned.

A decision from the high court is expected by the end of June – just in time for census questionnaires to be printed the following month.