According to reports, it is believed that the robocall was created artificially.

"Republicans have been trying to push nonpartisan and Democratic voters to participate in their primary. What a bunch of malarkey," says the message as quoted by BBC.

It is still not clear who created the audio.

The New Hampshire attorney general's office reacted to the development and issued a statement which read: "Although the voice in the robocall sounds like the voice of President Biden, this message appears to be artificially generated based on initial indications."

"The message appears to have been “spoofed” to falsely show that it had been sent by the treasurer of a political committee that has been supporting the New Hampshire Democratic Presidential Primary write-in efforts for President Biden. The message’s content directed recipients who wished to be removed from a calling list to call the number belonging to this person," the statement said.

The office said the messages appear to be an unlawful attempt to disrupt the New Hampshire Presidential Primary Election and to suppress New Hampshire voters.

"New Hampshire voters should disregard the content of this message entirely. Voting in the New Hampshire Presidential Primary Election does not preclude a voter from additionally voting in the November General Election," the statement said.

The investigation comes after a prominent New Hampshire Democrat, whose personal cellphone number showed up on the caller ID screens of those receiving the call, filed a complaint, reported NBC News.

The message concludes with a phone number belonging to Kathy Sullivan, a former New Hampshire Democratic Party chair who now runs a super PAC supporting the campaign to urge New Hampshire Democrats to write in Biden’s name in the primary, the news channel reported.

Kathy Sullivan described the act as an 'unpardonable sin'.

Kathy Sullivan posted on X: "Interfering with the right to vote is disrespectful to them, and an unpardonable sin. So, to whoever called NH voters and told them not to vote tomorrow? No matter what you may think, you aren't a patriot. You don't love freedom. You don't get what America is about."

Fraudulent calls ranged from 5,000 to 25,000

Anti-robocall application Nomorobo's CEO Aaron Foss told CNN their data showed that 76% of the robocalls targeted New Hampshire, with 12% directed at Boston and the remaining 12% covering other areas. 

The application estimated the number of these fraudulent calls ranged from 5,000 to 25,000.

The campaign of Rep. Dean Phillips of Minnesota, who is challenging Biden for the nomination, told NBC it was not aware of the calls.

“Any effort to discourage voters is disgraceful and an unacceptable affront to democracy,” spokesperson Katie Dolan told the news channel. “The potential use of AI to manipulate voters is deeply disturbing.”

A spokesperson for Trump’s campaign also denied involvement to the incident.