Ed Miliband has warned of signs of UK economic weakness, on his first visit to Wales as Labour leader.
Mr Miliband, who met business people in the Vale of Glamorgan, said unemployment should be falling faster.
He accused the UK government of taking a "big gamble" with the economy.
"What I see is an economy where there are real signs of weakness in terms of employment, in terms of growth and now inflation as well, " Mr Miliband told BBC Radio Wales.
"That's a bad combination."
He criticised the UK government and said there were "real signs of weakness" and it was making the wrong choices.
"I hope their gamble pays off but it is a big gamble."
His comments came after Justice Secretary Ken Clarke told the Daily Telegraph the middle classes were unaware of the scale of government spending cuts that will hit them this year.
Mr Miliband said: "Ken Clarke has warned this morning of some of the implications of the cuts being made. What you see is a government which has a plan to get rid of jobs in the public sector but not enough of a plan to replace them in the private sector."
Later, he said: "I think Ken Clarke needs to wake up and realise the middle classes across Britain are already very worried about the cuts and the impact they're having.
"That's why we're seeing such protests against, for example, the closure of local libraries that are happening across the United Kingdom."
"I hope that Ken Clarke's comments will make them think again and make sure that they have a plan B that they should be doing."
He said he welcomed all encouraging signs but the economy shrank in the last quarter, and part of the problem was too much money being taken out of the economy.
Mr Miliband also told BBC Radio Wales Labour in Westminster could emulate some of the policies of the Welsh assembly government and praised the way Welsh students are being protected from the hike in students fees and the continuation of the maintenance grant.
"I think we can learn from some of the things Carwyn [Jones] is doing here as first minister and the Welsh Assembly Government is doing but unfortunately are not happening in England," he added.
After meeting local business leaders in Barry, Mr Miliband travelled to Cardiff to give his support to the Yes campaign on assembly powers, ahead of the referendum on 3 March.
He used a question and answer session with Labour supporters at the Wales Millennium Centre in Cardiff to say he did not think the current way in which Welsh laws are made "'makes sense".
Mr Miliband said: "I'm for a Yes vote because the idea that Carwyn and other ministers in the Welsh assembly government have to come back to London for order-making powers when they want to change things in a devolved area doesn't make sense.
'Not really listening'
"When it's legislation that is only affecting Wales, it should be made in Wales...and that's why I'm supportive of a Yes vote in the referendum."
He also accused the coalition in Westminster of being a "Conservative-led government propped up by Liberal Democrats."
Mr Miliband told supporters: "I don't think this is fated to be a five year government. I think that we have a chance of stopping this being a five year government but only if the Liberal Democrats realise that Nick Clegg is driving them off a cliff."
Nigel Dix, of the No campaign, said of Mr Miliband's visit: "He's not really listening to all Labour activists, councillors and party members in Wales.
"They have grave concerns of what is happening to devolution in Wales and at end of day he's playing into the hands of the separatists within Cardiff Bay by supporting the Yes camp."
He said it was a "recipe for breaking up the United Kingdom in the long run".