Russian state-backed hackers who hacked the Democrats in 2016 have attempted a similar intrusion into computer systems of over 200 organisations, including political parties and consultants, tech company Microsoft has said.
The firm said the efforts seem to be part of a wider increase in targetting of US political campaigns and related groups.
“What we’ve seen is consistent with previous attack patterns that not only target candidates and campaign staffers but also those who they consult on key issues,” Tom Burt, Microsoft vice president, wrote in a blog post.
Most of the hacking attempts by Russian, Chinese and Iranian agents were halted by Microsoft security software and the targets informed, he said.
The company refused to comment on who may have been successfully hacked or the impact.
“This is the actor from 2016, potentially conducting business as usual,” said John Hultquist, director of intelligence analysis at the top cybersecurity firm FireEye.
“We believe that Russian military intelligence continues to pose the greatest threat to the democratic process.”
Mr Hultquist added that Microsoft's claim shows that Russian military intelligence continues to pursue election-related targets, undeterred by US indictments, sanctions and other countermeasures.
It interfered in the 2016 campaign - seeking to benefit the Trump campaign - by hacking the Democratic National Committee and the emails Hillary Clinton's campaign manager, congressional and FBI investigators have found.
The same GRU military intelligence unit, known as Fancy Bear, that Microsoft identifies as being behind the current election-related activity also broke into voter registration databases in at least three states in 2016 - though there is no evidence it tried to interfere with voting.