The far-right British National Party could win control in Burnley unless the voting system is changed, according to the Electoral Reform Society.
By Ben Davies
BBC News Online community affairs reporter
The organisation claims that under the first past the post system the BNP could end up in charge of Burnley borough council within two elections.
According to chief executive Ken Ritchie changing the voting system would hamper the party's progress.
"In Burnley there is a strong case for proportional representation," he said.
Mr Ritchie added: "Last year the BNP won six seats in the 12 wards it contested, inspite of having received little more than a third of the votes in these seats.
Luke Smith celebrates the beginning of his short career as a councillor
"If people vote the same way this year, the BNP will win a further six seats and in the following election we could see the BNP holding 100% of the seats in these wards with only a third of the vote."
In a report out on Tuesday, the Electoral Reform Society argues that supporters of mainstream parties would rather vote for "any other party than the BNP" and therefore a form of PR called STV, Single Transferable Vote, could be put to use.
"At present the votes of many people who oppose racism are wasted on losing candidates, but STV would allow those votes to be transferred to other candidates opposed to extremism. Using STV the BNP would only win those seats which its electoral strength justifies," according to the report.
The society also argues that PR would help give voters a greater sense of connection with their local authority.
The BNP was briefly the official opposition in Burnley after making gains in the local elections last May, although it lost that title to the Liberal Democrats in June.
That came when a BNP councillor, Luke Smith, was suspended from the party in August, following a brawl at its Red White and Blue festival.
He then resigned from the council, prompting a by-election which the Lib Dems won.