Following his high-profile TV debates with Nigel Farage over Europe, Liberal Democrat leader Nick Clegg has vowed to step up his campaign for Britain to stay in the EU.
Despite polls suggesting that viewers thought the Ukip leader trounced him in their two televised showdowns, the Deputy Prime Minister said he would make it a "personal priority" to travel the country making the case for Europe in the weeks before the May 22 elections to the European Parliament.
In a speech to the Welsh Lib Dem conference, Mr Clegg is expected to accuse David Cameron and Ed Miliband of putting "party before country" by ducking out of the EU debate, describing them as "absent, hiding, missing in action".
Mr Clegg will acknowledge that he did not defeat Mr Farage's eurosceptic arguments in their TV clashes, telling delegates in Newport: "Are we going to win that argument in 120 minutes? No, sadly not: the sceptics have been peddling their myths and assertions free from real challenge for years. And the isolationists have entrenched their views with skill - presenting themselves as the forces of freedom; annexing the language of patriotism; pro-Europeans should be in no doubt about the out-ers' appeal."
But will insist that the Farage debates were "just the start - a curtain-raiser to a campaign that will be the most passionate defence of British interests in Europe for generations".
Despite his poor post-debate polls, Mr Clegg will point out that the TV shows gave the Liberal Democrats an audience of millions of voters who heard him make "the case for In' and challenge Ukip's "dangerous vision for Britain".
And he will say: "Someone has to stand up for the Britain we love: a Britain that is open, compassionate and outward-facing; a Britain that embraces the future and continues to lead on the world stage.
"That someone has to be us. Britain only has one truly internationalist party. There's only one real Party of In.
"Where are the supposedly pro-European Labour party? Or the supposedly moderate Conservative leadership? The country is finally having it out about the single biggest issue facing our future - and where are they?
"Absent. Hiding. Missing in action. Paralysed by their own internal divisions. Too scared to speak up for the national interest because it'll cause them too great a political headache.
"It's party-before-country from leaders who sort of half say they're In, but who don't have the guts to actually come out."
Mr Clegg will promise to "fill the void" left by Labour and Conservatives by spending the next seven weeks spreading the "better off in" message through town hall meetings, radio phone-ins and knocking on doors during visits to cities around Britain.
"Millions of people have now heard us make the case for In. Millions of people have now seen us challenge Ukip's dangerous vision for Britain," Mr Clegg will say.
"Millions of people are watching as we interrupt the slow slide towards European exit, planting ourselves squarely between Britain and the door.
"And our challenge now is to seize on this momentum. I am making it my personal priority: I've taken on Farage and now I'm taking our message round the country."