Election 2015: Ed Miliband says no deal with Plaid Cymru
Ed Miliband has confirmed that his refusal to work with the SNP in a hung parliament also applies to Plaid Cymru.
Plaid leader Leanne Wood has said she could do a deal to put Labour in power even if the SNP was not involved.
She said Mr Miliband was irresponsible to rule out an SNP deal, claiming it could "open the door" to the Tories.
The Labour leader said he was "not interested in deals or coalitions", but in being "a Labour prime minister who puts forward a Labour programme".
Speaking at a Labour party rally in Cardiff on Friday, Mr Miliband said it was a "pretty dead cert" that David Cameron wanted to cut child benefit.
Accusing the Conservatives of planning to reduce tax credits for families if they win next week's election, the Labour leader said his first act as prime minister would be to find money to scrap the so-called bedroom tax.
Family finances, he said, were "on the ballot paper at this election".
Mr Miliband said: "For the hundreds of thousands of families in Wales, they should know David Cameron is planning to cut your child benefit. That is the choice in six days' time.
"You've got six days to save your child benefit, and the way to do that is to vote Labour.
"Because Mr Cameron denied he was going to means test child benefit at the last election and then did.
"He's not even denying further cuts to child benefit at this election. So it's a pretty dead cert that that is exactly what he's going to do."
Visiting the marginal Cardiff North seat for the Conservatives, Home Secretary Theresa May said Mr Miliband would need to negotiate with the Scottish nationalists on every parliamentary vote to run a minority government.
"He said there wouldn't be a formal coalition or a formal deal, but actually what has become clear from Nicola Sturgeon, but also from other members of the Labour shadow cabinet, is that there would be arrangements on a vote by vote, issue by issue basis," she said.
"So what we would see if Labour is in government is a Labour government propped up by the SNP."
That would mean higher taxes, more borrowing and "weaker defences", she said.
Mrs May also brushed off Labour's claims that her party would cut child benefit.
She said David Cameron had been "very clear, he rejected those plans when they were first proposed and he rejects them now".
She added: "If we've said that child benefit will be frozen that is a very real difference."
Elsewhere in the election campaign, Plaid Cymru leader Leanne Wood is promoting party pledges to scrap zero-hours contracts and raise the minimum wage.
Marking International Workers' Day, she said her party was committed to increasing the minimum wage of £6.50 an hour to the so-called living wage - currently £7.85 an hour - by 2020.
Ms Wood will also be taking part in the second and final TV election debate involving Welsh leaders of the six main parties in Cardiff on Friday evening.