Republican attorneys general are making a last-ditch bid to block the Obama administration from ceding U.S. oversight of the internet’s domain name system, filing suit in federal court ahead of an imminent deadline for the hand-off.

The AGs from Texas, Arizona, Oklahoma and Nevada asked a judge late Wednesday to step in and stop the transition to an international oversight body, after GOP lawmakers failed to stall the move as part of a short-term spending bill.

“Trusting authoritarian regimes to ensure the continued freedom of the internet is lunacy,” Texas Attorney General Ken Paxton said in a statement. “The president does not have the authority to simply give away America’s pioneering role in ensuring that the internet remains a place where free expression can flourish.”

Paxton was among the four Republican AGs who filed the lawsuit in U.S. District Court Southern District of Texas, Galveston Division.

The U.S. government has been in charge of domain names for more than three decades, thanks to a Commerce Department agency's oversight of an obscure, but powerful, Los Angeles-based nonprofit called the Internet Corporation for Assigned Names and Numbers (ICANN).

If the transfer takes place – as it is set to do on Oct. 1 -- the suit argues people will “lose the predictability, certainty, and protections that currently flow from federal stewardship of the Internet and instead be subjected to ICANN’s unchecked control.”

The suit argues the looming transfer violates the property clause in the U.S. Constitution which prohibits handing over government property without Congress’ approval. The suit also claims the handoff would violate First Amendment rights and says ICANN, the nonprofit owners in control, would be unchecked and could start to censor speech.

Plans to transfer control over functions -- like the directories that help web browsers and apps know where to find the latest weather, maps and Facebook posts – have been in the works since the 1990s.

Momentum grew following the Edward Snowden leaks about U.S. government surveillance, and the Commerce agency said it would cede oversight. Since then the administration has tried to fast-track the transfer as a sign that the U.S. government isn’t policing the internet -- and has disputed the warnings from Republicans and others.

In a blog post last month, Assistant Secretary for Communications and Information Lawrence E. Strickling said the transition marks the “final step” of a commitment that dates back nearly two decades.

He said the new model will maintain “the stability, security, and openness of the Internet that users across the globe depend on today.”

Republicans in Congress, though, have long-objected to the transfer, which they called a “giveaway” to the rest of the world. They argue that handing over control to a non-government entity would give countries like Russia and China the ability to control online speech – something supporters categorically deny.

The new lawsuit also claims ICANN “has a documented history of ignoring or operating outside of its governing bylaws.”

“Nothing protects the Plaintiffs from additional occurrences of ICANN oversight failures,” the suit says.

Mark Grabowski, an internet law professor at Adelphi University in New York, agrees.

“There is currently nothing prohibiting ICANN, post-transition, from eliminating or transferring what are essentially the Web addresses for U.S. government and military websites,” Grabowski wrote in InsideSources.com.

He added, “A company owned by or located in Russia or China could end up managing whitehouse.gov, fbi.gov or army.mil. Losing control of these web domains would put our nation’s security at risk.”

Sen. Ted Cruz, R-Texas, who aggressively campaigned against the transfer, called it a “a profound disappointment” when a measure stalling the move was left out of the latest government spending bill. He called the Obama administration’s actions “dangerous and indefensible.”

“Protecting free speech online should be an issue that brings Republicans and Democrats together,” Cruz told FoxNews.com in a written statement. “It’s an issue the American people overwhelmingly agree with and they expect us to defend internet freedom. That didn’t happen in the Senate’s continuing resolution and I think that was deeply unfortunate.”

FCC Commissioner Ajit Pai told the “Sean Hannity Show” on Wednesday that handing over the reins to ICANN is something that should worry anyone who cherishes “free expression, and free speech rights generally,” and could potentially cede oversight of the Internet to “foreign governments who might not share our values.”

Tech companies, however, have largely supported the plan.

In a Sept. 13 letter sent to Republican and Democratic leaders in Congress, the heads of Google, Facebook, Amazon and 20 other companies and trade groups urged lawmakers to support the plan.

FoxNews.com's Barnini Chakraborty and The Associated Press contributed to this report.