David Cameron has launched the Conservative campaign for this month's local and European elections with a warning that only the Tories can deliver economic revival and an in/out referendum on Britain's EU membership.
With his party trailing third behind Labour and the UK Independence Party in polls for the Euro-elections on May 22, Mr Cameron denounced Nigel Farage's party as "all talk and no delivery" and dismissed Labour as "all short-term gimmicks and no long-term plan".
Only the Conservatives' economic plan can maintain the "great British revival" seen in recent months, which have seen the UK economy growing faster than most of the developed world and achieving higher employment rates than the USA, he said.
And he argued that only a Conservative-led government can deliver the EU referendum which he has promised by the end of 2017, repeating his pledge that he will not serve as Prime Minister in any coalition administration which fails to uphold this commitment.
Launching the Tory campaign at a JCB construction vehicle plant in Newcastle-under-Lyme, Staffordshire, Mr Cameron took aim at his rivals: "Frankly I don't need to discredit Ukip - they do a good enough job themselves. Their own leader admits they 'cannot change a thing in Brussels'.
"This is who we're up against: Labour - all short-term gimmicks and no long-term plan. Ukip - all talk and no delivery.
"The choice is clear: If you want a serious party with a credible long-term plan and a party that's delivering on that plan, then you only have one choice: you have got to vote Conservative."
Ahead of polls taking place in local councils across England, the Prime Minister said that the effects of recovery were being seen in all parts of the country.
"Britain is coming back," he said. " We came through the Great Recession together. We are building the Great British revival together.
"And all this didn't just happen. The economic pendulum didn't just swing our way. It's happening because of the people in this country who worked their hearts out, the businesses that hung on through the hard times and yes - it happened because this is a Government with a long-term economic plan to secure Britain's future.
"And we've got to be very clear. The Great British revival doesn't come with a life-time guarantee. The job is not done. If we want to keep making progress, keep creating jobs and securing this country's future, then we've got to carry on working through the plan.
" And coming up to these elections on May 22, this is what our message is all about. C onservatives are the ones with a long-term plan to secure Britain's future and we are delivering on that plan."
Mr Cameron sought to counter the growing appeal of Mr Farage's eurosceptic party by highlighting his own record of "standing up" to Brussels by vetoing an EU treaty, cutting the budget and getting the UK out of the euro bailout scheme.
The Tory plan for Europe had "three words at its heart - Britain's national interest", he said.
"I have a track record of delivery - and believe me, whatever it takes, I will deliver this in-out referendum. L abour won't. Ukip can't. I will.
"Earlier this week I made clear I would not lead a Government that either could not or did not deliver an in-out referendum.
"Let me be absolutely clear. The British people need to have their say on our membership of the EU. For me this is a fundamental principle. And I would not be Prime Minister of a government unless we could carry out our pledge of an in-out referendum.
"Because the British people deserve their say. And I will make sure they get it."
A YouGov poll at the weekend put the Conservatives in third place in the Euro-elections, with 19% support, well behind Ukip on 31% and Labour on 28%.
Ukip responded to the Tory launch with another stark campaign poster highlighting immigration from the EU.
It shows an escalator running from the English Channel up the White Cliffs of Dover with the slogan: "No Border. No Control. The EU has opened our borders to 4,000 people a week."
Mr Farage said: "This is, in my view, the most powerful image of the entire European election campaign. It is designed to bring home to the British public just what membership of the EU means as regards controlling our own borders.
"The white cliffs of Dover have always been seen as symbolic of Britain's island status. That status should give us added ability to pick and choose the people who come to live and work in our country. But under EU free movement laws we have no serious control whatever.
"No doubt the political establishment will react again in mock outrage and throw a new round of slurs and smears at Ukip and at me.
"We've been called every name under the sun in recent weeks. But we will not be silenced, and we know that millions of decent British people are on our side and are grateful that we are speaking out."
For Labour, shadow Cabinet Office minister Michael Dugher said: "David Cameron is obsessing about Ukip rather than the cost-of-living crisis faced by British families.
"Once again, this is weakness not leadership. David Cameron is banging on about Europe, putting party interest before the national interest.
"With things getting harder, the big question at this election is who will best stand up for hard-working families, but David Cameron is in the pocket of the privileged few, in fear of Ukip and incapable of raising living standards for ordinary people."