Nick Clegg has accused Labour and the Tories of being more interested in their own internal politics than in standing up for Britain over the future of the country's place in Europe.
The Deputy Prime Minister accused David Cameron and Ed Miliband of "bowing their heads and averting their gaze" to avoid being drawn into the debate on the issue.
The Liberal Democrat leader will face Ukip's Nigel Farage in the second head-to-head showdown over the European Union on Wednesday.
An instant poll found that Mr Farage won the first debate, hosted by LBC Radio, with 57% of those questioned by YouGov for The Sun saying he performed best - against 36% for the Deputy Prime Minister.
But in an email to supporters, Mr Clegg insisted the debate showed that the Lib Dems were prepared to fight over the issue - unlike the Tories and Labour who were both "riddled with division" over Europe.
He said: " I am very proud that Liberal Democrats are prepared to stand up for Britain by issuing a full throated defence of our place in Europe. It's clear we're the only party prepared to do so.
"The Labour and Conservative leaderships are bowing their heads and averting their gaze, desperate for the debate to move on.
"They may hold different positions on the EU, but their leaderships are treating it in the same way: a problem they don't want to talk about.
"Both parties are riddled with division, more interested in themselves than standing up for our country.
"We are a party that knows, that to protect British jobs, to ensure our country is safe and to keep our standing in the world, we need to be in Europe, not out.
"And as you showed last week, we're prepared to fight for it."
Ahead of Wednesday's BBC debate with Mr Farage, he said: "Join me this week in making our voice heard and protect British jobs."