An army of Chinese-controlled social media bots is attempting to influence voters in Alabama, Texas and Tennessee, while denigrating US Senator Marco Rubio of Florida, according to new research published on Wednesday by Microsoft.

The operation represents a coordinated interference effort against down-ballot races, experts say, in which the fake accounts are denigrating representative Barry Moore of Alabama, representative Michael McCaul of Texas, Tennessee Senator Marsha Blackburn and Rubio, all Republicans.

The troll network has “parroted antisemitic messages, amplified accusations of corruption and promoted opposition candidates”, according to Microsoft.

The group allegedly responsible is known as Taizi Flood, which has been previously associated with China’s Ministry of Public Security, researchers say. The lawmakers were each targeted because they had denounced Chinese government policies historically, the report noted.

A spokesperson for China’s embassy in Washington said China “has no intention and will not interfere in the US election” and that such claims are “full of malicious speculations”.

Among other things, the bots criticised Moore’s support for Israel and used antisemitic language. Another collective of related accounts claimed Rubio was part of a financial corruption scheme.

The bots amplified support for Blackburn’s election rival while spreading claims she took money from pharmaceutical companies. With McCaul, they pushed narratives that he engaged in insider trading.

A spokesperson for Moore, Madison Green, said his office was aware of the campaign.

“We know that the CCP is antisemitic, so it isn’t surprising that they are targeting me and other politicians who support Israel to try to sow division in advance of the most important election in our lifetime,” said Moore, referring to the Chinese Communist party.

“China has made it clear they will use every weapon in their arsenal, including offensive cyber capabilities, to try and destroy democracy across the world,” he added.

In an emailed statement, McCaul said he considered the targeting a “badge of honour” as he’s made “standing up to the CCP a central part of my career”.

Spokespeople for the other two lawmakers did not immediately respond to a request for comment.

The Office of the Director of National Intelligence, which is coordinating the federal effort to defend the election from foreign influence, did not immediately respond to a request for comment.

Moore, McCaul and Blackburn are all running for re-election next month. Rubio, who serves as vice-chair of the Senate intelligence committee, is not up for re-election until 2028.

The Microsoft researchers found the influence effort did not result “in high levels of engagement”. The report did not provide any metrics for how many Americans viewed the relevant social media posts.