By politics.co.uk staff
The 'yes' campaign still has a clear lead in the AV debate, according to a new poll.
The Reuters/Ipsos Mori poll shows two in five people (42%) back a change to AV, while a third (35%) oppose it.
Young people and upper income groups are the most likely supporters.
Lib Dem supporters are easily the most supportive of the change, with 60% planning to vote 'yes'. Fifty-three per cent of Labour supporters will also vote yes.
Predictably, the Conservatives are the least likely to back it with just 22% of Tories backing a switch to AV.
But strategists will put particular emphasis on the fact that so many voters are undecided. One in five of the population - 21% - say they still don't know which way they will vote.
"There are still plenty of votes to be won for both the 'yes' and 'no' campaigns," said Helen Cleary, head of political research at Ipsos MORI.
"Even among those who are certain to vote, one in ten are undecided. People don't yet know much about the referendum and we could well see public opinion shift during the campaign."