Vote referendum: AV will boost BNP, says Baroness Warsi
Conservative chairman Baroness Warsi has said changing the UK voting system to the alternative vote (AV) would mean more votes and legitimacy for the BNP.
She told the Sun AV could see politicians "pandering to extremist voters" - but Lib Dem peer Baroness Falkner said the No campaign was resorting to "baseless scaremongering".
UK voters will be asked on 5 May whether they want to keep first-past-the-post system or switch to AV.
The BNP is against a switch to AV.
The decision to hold a referendum was a key coalition deal concession by the Conservatives - who back first-past-the-post - to the Lib Dems, who have long campaigned to change the voting system.
Voters will be asked whether they want to change the current system, where people put a cross by their preferred candidate, for AV, where candidates are ranked in order of preference.
In an article for the Sun, Baroness Warsi argues that the AV system - where, if no-one gets more than 50% of first-choice votes, the last placed candidate is eliminated and their second preferences are redistributed - means some people have their votes counted more than others.
She says: "Too often, those people tend to be the ones who vote for extremist parties. This means AV could see candidates pandering to extremist voters - because to win a seat they will need to win the support of people whose first choices have already been eliminated."
She also argued that the system risked giving parties like the BNP "more legitimacy" because people would be able to register a "protest vote without considering the electoral implications".
"The long-term effects of that are clear: more votes, more power, more long-term legitimacy for the BNP and other fringe parties," she wrote.
However the BNP says it will tell its supporters to oppose AV. It instead backs a system known as party list proportional representation, which is used in England, Scotland and Wales for elections to the European Parliament - the BNP has two MEPs.
The Yes to AV campaign said the Secretary General of the Muslim Council of Britain and head of Operation Black Vote both agreed that under AV, politicians would have to reach out further and secure majority support.
The campaign's chairman Katie Ghose said: "The No campaign can't choose their supporters, but they can't escape the fact the BNP are campaigning for a No vote. Maybe up is down and black is white, but [BNP leader] Nick Griffin is still saying No to AV."
And Lib Dem peer Baroness Falkner said: "I'm shocked and frankly appalled by the distortions being spun today by Baroness Warsi and the 'No' campaign.
"Under AV, no one can get elected unless the majority of people support them which quite obviously makes it harder, not easier, for extremist parties. That's exactly why the BNP are campaigning for a 'No' vote.
"The No-campaign has resorted to baseless scaremongering because they can't make any positive case for the status quo. People won't be fooled by this."
Earlier this week Baroness Warsi's Lib Dem coalition colleague, Energy Secretary Chris Huhne, wrote urging her, as a patron of the "No to AV" campaign, to stop it adopting "the politics of the gutter" with "misleading and scaremongering advertisements".
Anti-AV posters have claimed that a yes vote would cost £250m and deprive sick babies of treatment and soldiers of body armour.
In his letter the Energy Secretary warned that splits over the AV referendum "should not be a source of tension between us or risk breaking the coalition".
On Sunday Lib Dem Business Secretary Vince Cable told the BBC he was "pretty sure" the coalition would survive if the referendum resulted in a "no" vote.
But he added: "There is a lot at stake and that is why we are fighting hard for it."