The BNP has said the incident in which Gordon Brown called a pensioner a "bigoted woman" has opened a "window of opportunity for the party".
Mr Brown apologised over his comments caught on tape about Gillian Duffy.
In an e-mail to supporters, BNP leader Nick Griffin said his party would appeal to working class voters who have been offended by the comments.
Meanwhile, he has admitted manifesto claims that Britain is the most densely populated country in Europe are wrong.
In the e-mail, Mr Griffin revealed the party's funds were "stretched to the limit" and called for donations to fund newspaper adverts in key areas such as Barking and Dagenham, Stoke-on-Trent, Leicestershire, Manchester and Barnsley.
He wrote: "Our activists are already at full stretch and we have no spare finances to fund extra campaign material, so what we want to do is to raise enough extra funds to place newspaper adverts in a whole range of key target areas up and down the country."
Meanwhile, Mr Griffin admitted on BBC Radio 4's World At One claims over how heavily populated Britain was were wrong.
He said: "In fact it's England and Wales. England and Wales are more overcrowded than anywhere in Europe except for Malta," he said.
"It's a fault in the manifesto. I blame the proof reader."
He also said he could not tell if a caller to a BBC radio phone-in was British because he could not see what he looked like.
He told the man, who said three of his grandparents were born outside Britain, that he could class himself as "civically British" but not "indigenous British".
BBC News
