A federal judge will hear arguments Tuesday over whether a Watergate-era law prohibiting the government from collecting data on how Americans exercise their First Amendment rights bars President Trump’s Election Integrity Commission from American’s voting records.

U.S. District Judge Royce C. Lamberth of the District set the hearing Monday after Common Cause, a nonprofit government watchdog group, alleged that the Trump administration was violating the Privacy Act of 1974 by seeking the “quintessentially First Amendment-protected political party affiliation and voter history data” of every American.

The court could rule on the request for a temporary restraining order as early as Tuesday.

The action marks the latest attempt by opponents to block the commission’s request for the voting information of more than 150 million registered voters. Trump created the commission after alleging that widespread fraud cost him the popular vote in November.

State leaders from both parties have voiced objections to the effort’s potential to reveal personal information, suppress voter participation and encroach on states’ oversight of voting laws.

Administration officials have said 30 states have agreed to share at least some data, adding that the commission requested only publicly available data and would anonymize any information it released.

[Trump’s voter-fraud commission wants to know voting history, party ID and address of every voter in the U.S.]

Earlier in July, another federal judge in Washington rejected an effort by the Electronic Privacy Information Center to block the commission’s request. That judge ruled that the commission is not required to review the proposal’s impact on privacy because it is a White House advisory panel exempt from such requirements. EPIC has appealed that ruling by U.S. District Judge Colleen Kollar-Kotelly.

The Common Cause suit takes a different tack, arguing that the commission’s request is substantively unlawful, not just procedurally flawed.

The suit alleges that the commission, led by Vice President Pence, with Kansas Secretary of State Kris Kobach (R) as vice chairman, recently described new actions that it planned to take that make it less of an advisory board and more like a federal agency.

For example, the lawsuit states that at the commission’s first public meeting July 19, Kobach compared its work to an Interstate Voter Registration Crosscheck program that he runs as Kansas’ chief elections official, under which 30 states pool data to identify, purge, and potentially prosecute voters registered in two states.

The suit claims that Kobach also directed staff to collect “whatever data there is” within the federal government that “might be helpful” to the investigation, including information kept by the departments of Justice and Homeland Security and U.S. Census Bureau, including data about individuals’ immigration and citizenship status.

The suit also names as defendants DHS and the Social Security Administration, which keeps records of individuals’ deaths.

[Federal judge allows Trump commission’s nationwide voter data request to go forward]

“Most of the time, advisory bodies call experts … they don’t themselves assemble a national voter file with personal identifying information on more than 100 million people … or broadly compare hundreds of millions of records against data sets of hundreds of millions of other records, ” said Loyola University law professor Justin Levitt, a former U.S. Justice Department civil rights division attorney in the Obama administration who has questioned the commission’s request.

“That is much closer to what other agencies might do in the course of their official duties … such as conducting law enforcement duties,” Levitt said.

A spokesman for the commission did not immediately respond to a request for comment late Monday.

In a statement, Karen Hobert Flynn, president of Common Cause, said, “The commission cannot be trusted, it has already shifted its explanation on where, and how, this First Amendment protected data will be stored. This is an attempt to evade post-Watergate privacy laws and undermines our electoral system and the privacy rights of millions of Americans.”

Trump formed the Presidential Advisory Commission on Election Integrity in May after repeatedly suggesting that millions of illegal voters cost him the popular vote against Democratic presidential nominee Hillary Clinton. Studies and state officials of both parties have found no evidence of widespread voting fraud.

[Why almost every state is partially or fully rebuffing Trump’s election commission]

Trump has championed the commission’s work as a way to “strengthen up voting procedures” by identifying “vulnerabilities … that could lead to improper voter registrations and improper voting.” Conservative board members have advocated stricter federal election laws, alleging that a bias in U.S. enforcement has benefited liberals.

The panel’s June 28 letter to the states requested that they turn over “publicly available voter roll data,” including names, addresses, dates of birth, party registrations, partial Social Security numbers and voting, military, felony and overseas histories, among other data.

On July 10, the White House clarified that it had scrapped plans to use a Pentagon-operated website to accept the data and had designed a system inside the White House to take the submissions.

[Trump’s voter commission hasn’t even met — and it’s already off to a rough start]

Critics said the proposal would increase privacy risks to every registered voter, including in particular military families whose home addresses would be revealed, people whose partial Social Security numbers are used as passwords for commercial services, and people with felony convictions.

Opponents view the commission’s work as forming a pretext for federal laws to suppress voter participation, including by racial minority groups and poor people.

Kollar-Kotelly said EPIC could continue its lawsuit, but wrote that for now, the only added risk to privacy was if the White House computer systems are more vulnerable to security threats than those of the states, or that its de-identification process would be inadequate.

Kollar-Kotelly added, “To the extent the factual circumstances change, however — for example, if the … powers of the Commission expand beyond those of a purely advisory body — this determination may need to be revisited.”

The commission, which had asked states to hold off submitting the voter data the panel had requested pending the court decision, renewed its request on July 27.

[Trump challenges states on voter fraud: ‘What are they trying to hide?’]

Although the May 11 executive order stated that the commission would be supported by the General Services Administration — a federal agency subject to privacy requirements — the administration said in fact data would be downloaded onto White House computers, with an employee of Pence’s office and White House information technology staff responsible for collecting and storing it.

Common Cause questioned that arrangement, adding that White House Communications Agency, a joint-service military agency under the administrative control of the Defense Information Systems Agency — which is subject to the Privacy Act — provides information services for the president, vice president, and executive office of the presidency.

[Trump’s voting commission asked states to hand over election data. Some are pushing back.]