The Conservatives can win back voters who have deserted them in favour of the UK Independence Party, Home Secretary Theresa May has insisted.
UKIP made gains in local elections as the Tories lost control of 10 councils.
Senior Tory David Davis is calling for a planned referendum on the European Union to be brought forward to counteract the UKIP threat.
Mrs May dismissed the idea but said the public needed "greater certainty" that a referendum would happen.
She said Prime Minister David Cameron had made it clear a referendum on the UK's membership of the EU would take place early in the next parliament.
UKIP, which campaigns for the UK to leave the EU, averaged 25% of the vote in the wards where it was standing in Thursday's elections and won more than 140 seats.
In response to Mrs May's comments, UKIP leader Nigel Farage, said: "She is asking us to trust the PM on a matter of a European referendum. He has a remarkably bad track record of keeping his word on this particular matter."
In opposition, Mr Cameron promised to hold a referendum on the Lisbon Treaty amending the EU constitution but, once in power, said he was unable to do so because it had already been ratified.
'More straight talking'
Mr Davis, who lost the contest to become Tory leader to David Cameron in 2005, said UKIP's policies on law and order, immigration, taxation, foreign affairs, and Europe "mimic a simplified 1980s Tory manifesto".
Writing in the Daily Telegraph, he said the Conservatives must break the impression that they were "privileged and out of touch", "deal properly with fears over immigration" and urgently take steps to cut taxes.
There must be "more straight talking and fewer focus groups; more conventional Tory policies, not because they are Tory, but because they work; less pandering to metropolitan interest groups; and please, please, no more Old Etonian advisers".
The prime minister has pledged to hold an in-out referendum on the EU during the early part of the next parliament - by the end of 2017 at the latest - if the Conservatives win the next general election.
But he has first vowed to renegotiate the UK's position within the EU.
Mr Davis, however, said the vote should be held ahead of next year's European elections, "otherwise Nigel Farage will characterise those elections as 'the referendum the Tories wouldn't let you have'".
Mrs May told the BBC the party would learn lessons from the local elections and would work hard to bring back those voters who left the Conservatives and voted for UKIP.
She said she believed the timing of the referendum promised by Mr Cameron was right but that the party would look at giving "some greater certainty". And she insisted the referendum would be "on the basis of a renegotiated settlement".
"I think what we need to do is be able to show people that we will hold that referendum and we will hold that referendum after the next general election."
'Badly off track'
Former Conservative party chairman Lord Tebbit suggested Mr Cameron immediately put legislation in place to allow for a referendum and set a date for it.
That, he said, would present a real challenge to Labour leader Ed Miliband to make it known where he stood.
Lord Tebbit also accused Mr Cameron of going "badly off track" by veering too close to the Liberal Democrats. He said too many people were beginning to prefer what UKIP was offering - which he called the "politics of the common ground".
"Most people in the country agree we are being mucked around by our friends in Brussels... most people think that immigration is too high... most think that welfare has got out of kilter."
Earlier, Sarah Newton, the Conservative Party deputy chairman, said the government should consider bringing forward legislation in this parliament guaranteeing a referendum would be held.
But Mrs May refused to confirm this would happen.
BBC political correspondent Iain Watson said UKIP's performance also raised questions for Labour, with its internal debate over whether to call for a referendum on EU membership likely to heighten between now and 2015.
Contests took place in 27 English county councils and seven unitary authorities, as well as in Anglesey. About 2,300 council seats were up for grabs in England, in a major mid-term test for the coalition government.