A row has blown up between Conservative co-chairman Baroness Warsi and UKIP after she appeared to link the party's poll success to the decline of the BNP.
UKIP is on course for its best ever local election results - mainly at the expense of the Conservative Party.
Baroness Warsi said it was "interesting" how an increase in the number of UKIP candidates had coincided with a drop in BNP candidates.
Her comments prompted an angry Twitter outburst from a UKIP spokesman.
Gawain Towler called Lady Warsi a "bitch", prompting some of his 1,700 Twitter followers to criticise his "unparliamentary language". He quickly deleted the post and and apologised, tweeting: "Deleted, out of order on my part".
He later added: "Shouln't (sic) have said that, apologise."
UKIP's deputy leader Paul Nuttall also responded to Baroness Warsi's comments, calling them were "disgraceful" and "a sign that the Conservatives are very scared of UKIP."
Speaking on the BBC's election night coverage, Lady Warsi said: "Where UKIP is fielding candidates this time that the BNP did last time but they're not this time, I think that will have an impact."
She added: "There are members of UKIP who are from all sorts of political parties, but it is an interesting mix there in terms of the number of candidates."
The BNP is fielding 131 candidates at this year's local elections, far fewer than in previous years.
The anti-immigration party has blamed this on a cash shortage, but it has been rocked by defections and internal strife and appears to have focused its resources on the London Assembly and mayoral elections.
UKIP is fielding a record number of local election candidates, about 700, and is polling at about 14% in the areas where it is running candidates - ahead of the Liberal Democrats.
The party is attempting to broaden its message beyond its traditional anti-EU platform, with pledges to cut council tax and building more grammar schools but it has traditionally performed poorly at local polls.
Backbench Conservative MP Gary Streeter said Conservative supporters were sending a message to David Cameron that "they don't think our leadership is Conservative enough" by voting UKIP.
· All the latest election results are available at bbc.co.uk/vote2012