Updated at 3 p.m. with a statement from the Justin Nelson campaign.

WASHINGTON — Several Texas Democratic congressmen are calling on state Attorney General Ken Paxton to investigate a voter targeting firm said to have misused data from 50 million Facebook users, a request a Paxton aide is calling a “political stunt.”

The firm, Cambridge Analytica, provided voter targeting services for Texas Sen. Ted Cruz’s presidential bid before contracting with President Donald Trump’s campaign. The firm, controlled by GOP billionaire financier Robert Mercer and his daughter, Rebekah, has come under fire in recent weeks amid reports that it used Facebook users' data for political purposes without their consent. Facebook said that was a violation of its terms of service.

In a letter to Paxton this week, San Antonio Rep. Joaquin Castro and five other Texas Democratic congressmen urged Paxton to investigate Cambridge for potential violations of data privacy and election laws. In the letter, the lawmakers noted that attorneys general in blue states including Connecticut, Massachusetts and New York have opened investigations.

“The office of the Attorney General has an obligation to ensure that Texans data has not been misused,” wrote Castro, along with Houston Reps. Gene Green and Al Green; Austin Rep. Lloyd Doggett; McAllen Rep. Vicente Gonzalez; and Brownsville Rep. Filemon Vela.

The men also noted a report by British broadcaster Channel 4 that captured Cambridge's now-suspended CEO, Alexander Nix, boasting of using bribes and women to entrap political opponents.

“Bribes to elected officials, sending women to seduce political opponents, and shell companies to hide their involvement in campaigns seems to be how Cambridge Analytica does business,” the Texas lawmakers wrote, adding: “Campaigns in our state must be free of nefarious actors masquerading as political strategists.”

The Texas Democratic Party has also called for Paxton to open an investigation.

Their requests have little chance of success. The Dallas Morning News reached out to the Texas attorney general's office, but a campaign spokesman weighed in on behalf of the Republican state official, calling the Democrats' letter a "political stunt."

Texas Attorney General Ken Paxton announced Texas' lawsuit to challenge President Barack Obama's transgender bathroom order during a news conference on May 25, 2016. Texas and several other states sued the administration over its directive to U.S. public schools to let transgender students use the bathrooms and locker rooms that match their gender identity. (Jay Janner / The Associated Press)

“Where was Congressman Castro’s concern for privacy and data breaches when the Obama campaign was mining voters’ personal data? This charade is nothing more than a political stunt, but it’s good to know that Mr. Castro is, at last, concerned about election integrity,” said Matt Welch, spokesman for Paxton’s campaign.

Given the mounting scrutiny on Cambridge and Facebook from dozens of state attorneys general and a federal agency, Austin attorney Justin Nelson, the Democrat challenging Paxton in November, said it was "dismissive and irresponsible" for the attorney general to deride the lawmakers' plea. "Texas needs to investigate this breach," he said in a statement Wednesday.

Double standard?

Welch, the Paxton aide, is among those pointing out what many say is a double standard over criticism of Cambridge, as the Obama campaign was hailed for its use of social media data in the former president’s election.

A difference, experts say, is in how the campaigns accessed the data, and their levels of transparency.

Cambridge, according to Facebook, acquired its data through a University of Cambridge psychology lecturer who developed a personality prediction app called “thisisyourdigitallife.”

The professor billed the product as a “research app used by psychologists." About 270,000 people downloaded the app, unaware that it would be used by a third party to harvest data on their friend networks and that it would be transferred and used in political campaigns.

The Obama campaign also acquired data using a Facebook app, but with the stated purpose of supporting a political campaign, according to Politifact.

The fact-checking outlet reports that the app “asked users’ permission to scan their photos, friends lists, and news feeds” and that most complied. That said, while the people who downloaded the app knew it was for a political campaign, their friends did not, according to the report.

The Cruz campaign did not respond to a request for comment about the call for Paxton to investigate the firm. A spokeswoman for Cruz previously said that when the first reports emerged in late 2015 that the firm was misusing Facebook data, Cambridge “assured” the Cruz campaign the allegations were false.

A former spokesman for the campaign has also publicly said that the Cambridge data was unreliable and that the Texan’s campaign used its own.

The Cruz campaign paid Cambridge Analytica $5.8 million between July 2015 and June 2016 for services that included "voter ID targeting," "voter modeling" and "survey research/donor modeling," according to federal election reports. Federal records show no sign of ties between any Cruz campaign and Cambridge since mid-2016.

Privacy debate

The issue has sparked a broader debate about data privacy in the age of social media. And Facebook itself has come under greater scrutiny, with the Federal Trade Commission announcing this week that it is investigating the tech giant over its privacy practices and whether it violated a consent order to disclose uses of customers’ data, according to The Associated Press.

The AP reported that Facebook didn’t tell the 50 million users affected by Cambridge that their data had been used in ways without their permission, and failed to verify that Cambridge destroyed that information.

Nearly 40 state attorneys general have sent letters to Facebook about its data policies and what it knew about the Cambridge Analytica scandal, according to the news outlet.

Facebook CEO Mark Zuckerberg is reportedly planning to testify before Congress, according to CNN, though details have not been confirmed.