Pennsylvania Attorney General Josh Shapiro, right, accompanied by Maine Attorney General Janet Mills, left, speaks at a news conference near the White House, Monday, Feb. 26, 2018 in Washington.

Gun control proponents and state officials are racing the clock to try to block blueprints to make guns from 3-D printers from going online Wednesday.

The varied efforts, in courthouses and legislatures, are aimed at Defense Distributed, a Texas-based nonprofit organization that won permission last month from the State Department to post schematics for homemade firearms. The largely plastic guns would be invisible to background checks and untraceable by law enforcement.

On Monday, nine states and the District of Columbia filed a joint lawsuit in federal court in Seattle calling on the Trump administration to stop the plans from being posted, and seeking a nationwide temporary restraining order. The action was filed by Bob Ferguson, the attorney general of Washington State, who said, "If the Trump administration won't keep us safe, we will."

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Joining were attorneys general from California, Connecticut, Maryland, Massachusetts, New Jersey, New York, Oregon and Pennsylvania.

President Trump said on Tuesday that these guns did not "seem to make much sense." In a Twitter post, Mr. Trump said he was looking into the matter and had already spoken to the National Rifle Association.

@realDonaldTrump: I am looking into 3-D Plastic Guns being sold to the public. Already spoke to NRA, doesn't seem to make much sense!

Separately, 21 state attorneys general sent a letter to the attorney general, Jeff Sessions, and the secretary of state, Mike Pompeo on Monday, saying that the State Department's decision was "deeply dangerous and could have an unprecedented impact on public safety."

In Pennsylvania, state officials on Sunday won a temporary agreement from Defense Distributed to bar state residents from downloading the plans.

Josh Shapiro, the Pennsylvania attorney general, said the idea of publishing how-to manuals for printed guns is "an obscene proposition" that "may seem like a joke, based on how outrageous it is," he wrote in a series of posts on Twitter on Sunday.

"We will do whatever is necessary to ensure that people can't just print a deadly weapon on a whim," he wrote. "Once they are out on the streets of PA, we'll never get them back."

But Cody Wilson, who founded Defense Distributed, said he would file a motion to free his company from the agreement.

"I'm not worried for me, I'm worried for the people of Pennsylvania, which is creating bad laws for their citizens," Mr. Wilson said on Monday. "Honestly, it's kind of sad."

The battle dates to 2013, when the State Department ordered Mr. Wilson to remove from his website plans for making guns with a 3-D printer, saying that they violated export regulations dealing with sensitive military hardware and technology.

Mr. Wilson sued in 2015, arguing that his weapons' plans were a form of speech and that his First Amendment rights were being stifled. In June, the government entered into what it called a voluntary settlement of the case following negotiations, and agreed to pay nearly $40,000 of Mr. Wilson's legal costs. Mr. Wilson said he would make the plans available on Aug. 1 — the day, his website said, when "the age of the downloadable gun formally begins."

In fact, the site began offering the plans late last week, and by early Monday evening, blueprints for 3-D printed AR-15 semiautomatic rifles had been downloaded more than 2,500 times, according to Mr. Wilson. Other gun blueprints have been available in dark corners of the internet for years.

The firearms can be printed without the serial numbers required of licensed manufacturers, leaving the guns invisible to background checks and untraceable by law enforcement, earning them the name ghost guns.

Gun control activists and law enforcement officials fear that criminals seeking guns will be able to bypass background checks, skirt age restrictions and ignore gun licensing rules. And some believe that the settlement with Mr. Wilson represented an abrupt about-face orchestrated by gun industry proponents in the Trump administration.

In New York, state lawmakers announced legislation on Monday that would require makers of ghost guns to have a gunsmith license and register the firearms. On Capitol Hill, two Democratic congressman, David Cicilline of Rhode Island and Seth Moulton of Massachusetts, said they planned to introduce a bill on Tuesday that would prohibit 3-D printed plastic guns that cannot be detected in standard security screens.

On Friday, nine senators wrote to Mr. Pompeo asking for insight into how the settlement was reached and where the money to cover Mr. Wilson's legal costs came from. The day before, more than 40 House members called for a hearing on the settlement.

But several efforts to stymie Defense Distributed have already hit roadblocks.

Last week, a federal judge in Texas denied, on procedural grounds, an emergency motion for a temporary restraining order against the company filed by three groups: Everytown for Gun Safety, the Brady Campaign to Prevent Gun Violence and the Giffords Law Center to Prevent Gun Violence.

Avery W. Gardiner, co-president of the Brady Campaign, called the decision "bitterly disappointing" but pledged that "this fight has only just begun."

Mr. Wilson has sued local officials in New Jersey and California who threatened legal action against Defense Distributed if online gun blueprints were made available in their jurisdictions.

"They've used their powers of office to threaten my legal activity with vague claims of breaking the law," Mr. Wilson told The New York Times. "It's a far reach for these state officers to say they have a power that trumps the First Amendment. They're trying to shut down a website."