According to a Department of Homeland Security spokesman, the agency branch responsible for cyber protection of US infrastructure has provided or will provide its services to only 21 states.
DHS officials are able to assess a state’s vulnerabilities to vote hacking and other illicit activities such as phishing.
Larry Norden, of the Brennan Centre for Justice’s Democracy, told Abc News: “The first thing that every state should be doing, and frankly not just the state but the counties to the extent they can, is to do a threat analysis to understand what the vulnerabilities in their systems are.”
He added: “Our election infrastructure is very complex, and it’s not always obvious where they are.”
Mr Norden’s remarks come amid growing concerns Russia may interfere the US midterm elections.
According to the Washington DC-based think tank Centre for Strategic and International Studies (CSIS), over 80 percent of cybersecurity experts say Russia is the biggest threat to the US midterm elections due to their various intelligence operations and attempts at espionage against political candidates.
A third of analysts also believe Russia could potentially target voting systems and voter registration lists.
In January 2017 a joint report produced by the CIA, FBI and other security agencies concluded that Russian interference ahead of the 2016 presidential election had been designed to help Trump and harm Hillary Clinton.
However, since the midterm elections are managed by state and local officials, the Department of Homeland Security can only offer its services to states and not impose them.
US Secretary of Homeland Security Kirstjen Nielsen noted “there are some states that are utilising the National Guard” instead of “working with us”.
She said: “There’s a variety of ways in which you can bring your capability and capacity up to speed.
“Each state is doing it a little bit differently.”
Mr Norden suggested it is not extremely concerning the Department of Homeland Security is not providing its services to every state.
However, he claimed it is hard to assess how prepared US elections officials are for vote hacking.
He said: “DHS is not the only source for doing good risk assessments, but they are one, and they’re free.
“Hopefully if they are using outside vendors or other IT experts, they’re getting good people to do that.”