A tiny branch of the U.S. Commerce Department is preparing to hand over control of the Internet’s “address book”—the highest level of the Domain Naming System, or DNS—to the Internet Corp. for Assigned Names and Numbers, a Los Angeles-based international nonprofit, effective Oct. 1, Ars Technica reports.

Republican lawmakers have tried to block the move, with the attorneys general for Arizona, Oklahoma, Nevada and Texas filing a lawsuit in a Texas federal court Wednesday, according to Politico.

The lawsuit contends that the transition amounts to the illegal giveaway of U.S. government property. The plaintiffs also fear that ICANN could prohibit speech on the Internet and revoke the U.S. government’s exclusive use of .gov and .mil domains.

Republican presidential candidate Donald Trump’s campaign weighed in on the issue, according to Ars Technica:

The Republicans in Congress are admirably leading a fight to save the Internet this week, and need all the help the American people can give them to be successful. Congress needs to act, or Internet freedom will be lost for good, since there will be no way to make it great again once it is lost.

Ars Technica also reports comments that Sen. Ted Cruz (R-Texas) made in a recent speech on the Senate floor:

Today our country faces a threat to the Internet as we know it. … If Congress fails to act, the Obama administration intends to give away the Internet to an international body akin to the United Nations. I rise today to discuss the significant, irreparable damage this proposed Internet giveaway could wreak not only on our nation but on free speech across the world.

ICANN says that these assertions by Republicans are unfounded.

“The US government has never, and has never had the ability to, set the direction of the (ICANN) community’s policy development work based on First Amendment ideas,” ICANN said in a statement, as reported by Ars Technica. “Yet that is exactly what Senator Cruz is suggesting. The US government has no decreased role. Other governments have no increased role. There is simply no change to governmental involvement in policy development work in ICANN.”

The change has been characterized as a symbolic takeover. The only thing that changes, according to Ars Technica, is that the U.S. will not have oversight over a contract between ICANN and Virginia-based company Verisign over the maintenance of the Internet’s global DNS.

Facebook, Amazon.com, Google and Twitter are some of the bigger tech companies that back the change, according to Ars Technica. They say it is imperative that Congress not block it.