Vote change ballot set to clash with assembly elections
First Minister Carwyn Jones wants May's Welsh assembly election put back to June to give a greater gap after a likely March referendum on more powers.
The BBC understands another referendum on the alternative vote (AV) system called by the UK government could be held in between, on 5 May.
Mr Jones has asked Welsh Secretary Cheryl Gillan to delay the assembly election until June.
Tory assembly leader Nick Bourne said it had all-party support in Wales.
Deputy Prime Minister Nick Clegg is expected to announce that a vote on the AV system could now happen on the first Thursday in May.
It throws up the scenario of voters in Wales possibly facing three trips to the polling booths in a matter of months.
A referendum is also expected next spring on more powers for the assembly.
Mr Jones said he discussed the possibility of putting the assembly election back a month with Mrs Gillan, but had yet to get a response on the matter.
Mr Jones said he had also written to fellow party leaders in the assembly in a bid to gather cross-party support.
Both Plaid Cymru and the Conservatives indicated their support, but the Welsh Liberal Democrats had not responded, he said.
Meanwhile, Mrs Gillan is not expected to comment on the issue ahead of any official announcement.
Labour's Caerphilly MP Wayne David warned of "information overload" with two votes on the same day.
Mr David, Labour's general election co-ordinator in Wales, said: "My concern is that if the AV referendum is held on the same day, there will be a UK wide debate and the issues particular to the Welsh assembly will be lost. That's a very big concern," he said.
"In the ideal world I would personally like to see a delay in the assembly election.
"I think that makes a great deal of sense. I know that many people in the Welsh assembly think that's the case as well."
Last month, Mrs Gillan confirmed that a referendum on whether the assembly should get more law-making powers will be held in the first quarter of 2011.
However, speaking in May, Welsh Lib Dem leader Kirsty Williams stated that the timing of that vote remained crucial.
"There is cross-party consensus that the referendum should not be held on the same day as the elections to the National Assembly," she said.
According to BBC Wales' political editor, Betsan Powys, one possible scenario is for the vote on extra assembly powers to be held in March next year, the referendum on AV in May, and the election for new assembly members delayed until June.
However, writing on her blog, she asks: "Won't it be quite tough to argue for paying to hold three votes in Wales within three months?"
The decision on whether assembly elections should be delayed rests with Mrs Gillan, and the leader of the Conservatives in the assembly, Nick Bourne, said he had called on the assembly government to enter talks with the UK government on the issue.
"I actually wrote to Carwyn Jones yesterday, and I'm going to make the letter available to the press, asking for a delay in the elections," said Mr Bourne on Friday.
"My party indicated some time ago that we wanted a delay, that's been conveyed to the First Minister and Ieuan Wyn Jones, and I've urged them now to give that message to Cheryl Gillan.
"Because I think she needs to know that all four parties want this delay, because clearly she won't act without this information."
But the Plaid Cymru AM Nerys Evans claimed the likely announcement on an AV referendum showed that Wales had not been considered by the UK cabinet.
"It's bizarre. The Electoral Commission has ruled previously and I think the Tories and Lib Dems supported the fact that it is very confusing having more than one election on one day.
"It clearly shows that there is no voice from Wales at all around the cabinet in London representing Wales and telling and explaining to the cabinet in London that we've got assembly elections at the start of May."
A spokesperson for the assembly government added: "There should be no distraction from the national assembly election.
"That is why we have agreed with other parties in the Assembly that our own referendum should not be held on the same day as the Assembly elections.
"The first minister therefore intends to make clear to both the prime minister and the secretary of state for Wales at the earliest opportunity that we are strongly opposed to the AV referendum being held on the same day as the Assembly elections."
The Electoral Commission said it would consider any proposal to hold a referendum on the same day as an election and advise "on how to make sure that it is well-run and delivered in a way that is easy for voters to understand and participate in".
A spokesman said: "There are benefits of holding elections and referendums on the same day - for example to encourage turnout, but there are risks associated with combination too."