"There has been a pact of silence on Brexit between Theresa May and Jeremy Corbyn," the Liberal Democrat Europe spokesman said in London on Tuesday. "It is one of the most cynical acts of political collusion between the two larger parties in a generation.
"Strip away the contrast in tone and the differences in language and a striking reality emerges: both the Conservative and Labour positions on Brexit are now more or less identical.
"Pull Britain out of the Customs Union and the Single Market. Abruptly bring an end to freedom of movement. Deny the people any chance to decide on the final deal. They are in total agreement."
Clegg also claimed that families across the UK will face a "Brexit squeeze" to their finances when the country splits from the EU.
"With average earnings growth failing to keep up with prices, consumers are already beginning to feel the Brexit squeeze," he said.
"Price rises have hit energy bills, petrol, and clothes. It's enough to make anyone need a fortifying glass of wine - but last week it was reported that the average price of a bottle of wine has hit its highest price ever."
The Liberal Democrats have campaigned on a pro-EU ticket throughout, with the party calling for a second referendum on the terms of the Brexit deal from Brussels.
But the Liberal Democrats may only make marginal gains on their 2015 general election performance, when the party won 7.9% of the vote. The latest opinion poll from ICM, of 2,000 people between 2 and 4 June, put the Liberal Democrats on 8%, Labour on 34% and the Conservatives on 45%.