According to the BBC/Sky News/ITV poll released at 10pm, the Conservative Party will lose the slim majority it won in 2015, falling 12 seats short of the 326 needed for a majority.
Reacting to the poll on ITV News, Osborne said it was “difficult to see how the party would put together a coalition”, adding that the results would be “on a real knife edge”.
The former Tory front-bencher - now the editor of the London Evening Standard - also said that the results could be worse for the Conservatives than the poll suggests, with a Tory politician in a university town telling him there had been a large youth turnout.
More than one million under 25s registered to vote in the election - more than any other age group.
Also appearing on ITV’s election coverage, former Labour shadow home secretary Ed Balls said “there will be a second election soon” if the exit polls are correct.
“If this is right, this is a very turbulent period for British politics,” Balls said.
“This looks like 1974,” he added. “A Conservative prime minister who didn’t need to call an election... who has been given a real kicking by the British people.”
The first result is due to be declared at 11pm in Houghton & Sunderland South, followed soon after by Sunderland Central.
HuffPost UK has live coverage of the night as the results roll in on our live blog here.