Conservative leader David Cameron today denounced the British National Party as a "completely unacceptable" organisation which "thrives on hatred".
He urged voters to back any other party rather than the BNP and said he hoped that the far-right grouping did not receive a single vote in the English local elections next month.
Mr Cameron's attack came as an opinion poll suggested that the BNP may be heading for its largest-ever electoral breakthrough on May 4.
The survey for the Sunday Mirror found that 45.5% of those certain to vote in the key battleground borough of Barking and Dagenham said they would cast their ballot for the BNP.
The poll put the BNP ahead of Labour, on 36.3%, the Tories (12.7%) and the Liberal Democrats (4.5%) in the east London borough.
If the survey result is reflected in voting on May 4, it could see many of the 13 candidates fielded by the BNP winning seats on the council and would probably make the party the official opposition to Labour.
The survey comes a week after Barking's Labour MP Margaret Hodge warned that eight out of 10 white voters she spoke to were tempted to switch to the BNP because of local concerns over housing and immigration.
And it comes ahead of a report from the Joseph Rowntree Charitable Trust expected to suggest that up to one in four voters across Britain would be willing to consider voting BNP.
A Conservative MP today warned that voters were drifting to the BNP because of mainstream parties' failure to reflect their concerns over immigration and race relations.
White voters were afraid of the forces of "political correctness" which could see them lose their job or face prosecution for comments they make about people from ethnic minorities, said Shipley MP Philip Davies.
"People feel nobody is standing up and talking about (asylum and immigration) issues," Mr Davies told The Observer. "They feel the only way they've got now to express their opinions is to put a cross in a secret ballot for the BNP.
"The fear is that if you are white and you say something that may be considered derogatory by somebody about an ethnic minority, you are going to be sacked or locked up."
Although he made no direct mention of Mr Cameron, Mr Davies' remarks will be seen as an implicit criticism of the new leader's decision to take the Conservatives towards the centre-ground by focusing on issues like the environment rather than traditional Tory concerns like immigration.
Mr Cameron insisted he was reaching out to voters in the inner-city seats targeted by the BNP and making a determined effort to increase Tory presence in urban areas.
And he told Sky News' Sunday Live: "The BNP is a party that thrives on hatred, that wants to set one race against another.
"I hope nobody votes for the BNP. I would rather people voted for any other party.
"I think they are completely unacceptable in their views and they thrive on hatred."
While electoral support for the far-right group has so far been limited to a few pockets of the country and just 350 BNP candidates are standing for election next month, today's poll suggests it may increase the tally of 15 council seats it currently holds across England.
Labour has 43 of the 51 seats on Barking and Dagenham Council, all of which are up for grabs on May 4.
The Sunday Mirror also surveyed three BNP target seats in Bradford, finding that 7% of those planning to vote said they would back Nick Griffin's party - almost double their 4.3% share of the national vote in the 2005 General Election.
Dagenham's Labour MP Jon Cruddas said: "It has sounded recently as if a vote for the BNP is some sort of legitimate protest vote. Let's get something straight. It is not."
Shadow home secretary David Davis described Mr Davies as "a very independent-minded character".
"What he said in the middle of it was that David Cameron and he agreed on immigration...about the need to control immigration in order to get good race relations within the country," Mr Davis told ITV's Jonathan Dimbleby programme.
He added that Mr Davies was addressing a general feeling that talking about certain issues was prohibited.Reuse content