Bernie Sanders, the rising presidential hopeful, has hit back at a donor to his Democrat rival Hillary Clinton after the group launched a 'vicious attack' over his support for the new British Labour Party leader Jeremy Corbyn.
A so-called super-PAC, Correct the Record, had reportedly sent an email to journalists, seizing on some of Mr Corbyn's more controversial moments, such as his dialogue with Hamas and the questioning of the legality of Osama bin Laden's killing, after the Vermont senator said he was "delighted" to see the British left-winger storm to victory on Saturday.
The email takes the so-far amiable Democratic race into more hostile territory more often seen within the Republican contest, though the Clinton campaign itself is yet to personally attack Mr Sanders directly.
Mr Sanders emailed his supporters today to condemn Correct the Record. He said: "Yesterday, one of Hillary Clinton’s most prominent super PACs attacked our campaign pretty viciously. They suggested I’d be friendly with Middle East terrorist organizations, and even tried to link me to a dead communist dictator.
"It was the kind of onslaught I expected to see from the Koch Brothers or Sheldon Adelson, and it’s the second time a billionaire super PAC has tried to stop the momentum of the political revolution we’re building together."
Hitting out at 'super PACs' - a group that can raise unlimited amounts to donate to political campaigns but which are prohibited from having any formal links to the candidate - Mr Sanders urged his supporters to donate $3 each to show that they have "had enough of the billionaire class buying elections".
Mr Sanders had welcomed the election of Jeremy Corbyn, the socialist outsider who swept in to win a landslide victory in the British Labour elections on Saturday, saying in a statement: "At a time of mass income and wealth inequality throughout the world, I am delighted to see that the British Labour party has elected Jeremy Corbyn as its new leader."
The Senator's polling numbers from New Hampshire and Iowa puts him on top of the Democrat leader board, according to the first wave of the YouGov/CBS News 2016 Battleground Tracker, which polled primary and caucus voters from both states.