Current and former election administrators said it would be virtually impossible for a foreign country to produce and mail in phony absentee ballots without detection, an issue Attorney General William P. Barr raised as a serious possibility in an interview published Monday.

Barr told the New York Times Magazine that a foreign operation to mail in fake ballots was “one of the issues that I’m real worried about.”

“We’ve been talking about how, in terms of foreign influence, there are a number of foreign countries that could easily make counterfeit ballots, put names on them, send them in,” Barr said. “And it’d be very hard to sort out what’s happening.”

Barr did not offer any evidence of how such a scenario would take place.

Elections officials in multiple states said it would be virtually impossible for a foreign government to achieve what Barr described.

Judd Choate, the elections chief in Colorado, where nearly all voters cast ballots by mail, said “there is zero chance” it could happen in his state because of security precautions in place there.

States use a variety of safeguards to confirm the validity of mail ballots. In about half the states, ballot envelopes bear a tracking bar code or tally mark that is unique to each voter. About 15 states require signatures to be matched against voter registration. Ballots are rejected if they are not sent in regulation envelopes that vary widely from state to state in format, size and paper stock. And there is little chance, administrators said, that election officials would not detect a surge of duplicate ballots arriving from the same voter.

“There isn’t an election office in this country that doesn’t know how many ballots they’ve mailed out, how many they’ve gotten back in, and who they were sent to,” said Tammy Patrick, a former election official with Maricopa County, Ariz., and now a senior adviser to the bipartisan foundation Democracy Fund. “It is absolutely not the case that someone could create a multitude of ballots and in some way infuse them or inject them into the system without detection.”

The Justice Department did not respond to multiple requests for comment about why Barr said he was concerned such a scheme could easily happen.

The country is expected to see a surge of mail ballots this year after nearly 30 states have already changed rules or practices in response to the public health threat posed by the novel coronavirus. President Trump’s campaign and the national GOP have launched a major effort to prevent the expansion of voting by mail, claiming it could lead to widespread fraud.

Like Trump, the attorney general has himself voted absentee. State voting records show that Barr, a resident of Fairfax County, Va., in the suburbs of Washington, voted by mail in 2019 and 2012. Trump cast an absentee ballot in Florida’s March primary.

Barr’s comments could serve to sow doubt about the integrity of the nation’s election security, much as Trump has with a barrage of unfounded claims about widespread fraud, voting rights activists said.

“The emphasis should be on protecting the right to vote and protecting electoral integrity, not creating boogeymen,” said John Powers, a voting rights attorney with the Lawyers’ Committee for Civil Rights Under Law.

States that vote entirely by mail have developed extensive security measures to protect the vote.

In Colorado, ballot envelopes feature tally marks that are unique to each voter, Choate said. Voter signatures are matched to those on file. Bad actors would have to replicate those marks, create ballots and envelopes made of the same paper and with the same design as authentic ones, and accurately forge signatures.

“It’s preposterous to the point of humor,” Choate said.

Even in states without all of those steps, those trying to counterfeit ballots would have to know the names and addresses of registered voters. And an onslaught of forged ballots duplicating ballots received from actual voters would almost certainly raise red flags in local election offices and prompt intensive investigations, officials said.

“While it’s difficult to comment on a hypothetical situation and we can only speak for North Carolina, it’s almost inconceivable that a county board of elections wouldn’t immediately detect ‘counterfeit ballots’ arriving at their offices,” said Patrick Gannon, a spokesman for the North Carolina State Board of Elections. “The county boards of elections send ballots out to those who request them.”

Chris Davis, the chief of elections in Williamson County, Tex., outside of Austin, said ballot envelopes are coded in his state, as well.

“When I get these questions I usually say, ‘Anything’s possible, but it’s not easy to do,’ ” he said.