He told LBC on Tuesday that a potential surge in popularity for the Brexit Party or Liberal Democrats could make it harder for either of the two main parties to win a parliamentary majority.
“I will make a prediction,” he told presenter Shelagh Fogarty, “There are going to be a record number of non-Conservative and non-Labour MPs as a result of this election.
“That makes it difficult for the Tories and Labour to win an overall majority.”
"The SNP look set to win the vast majority of seats in Scotland,” he added.
“The Liberal Democrats given their position in the polls should do extremely well. We expect Caroline Lucas and the Green Party to hang on to her seat.
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"We could have more than 100 MPs that do not belong to either of the other two parties.”
The Conservatives will go into a likely December general election with a double-digit lead in the opinion polls.
The party is currently around 15 points ahead of Labour.
It is the biggest lead the Tories have enjoyed for nearly three years.
The Press Association’s latest poll has the Conservatives averaging 38 per cent, with Labour on 23 per cent, the Liberal Democrats 18 per cent and the Brexit Party 11 per cent.
Polling agency YouGov meanwhile predicts the Tories will win 36 per cent of the vote, with Labour taking a 23 per cent share. Their projections also put the Lib Dems on 18 per cent and the Brexit Party on 12 per cent.
At the start of Theresa May’s ill-fated 2017 general election campaign, the Conservatives had a poll lead over Labour that averaged 20 points.