Labour leader Ed Miliband believes Wales does not need further legislative powers - but says he will be guided by First Minister Carwyn Jones if the system requires change.
Mr Miliband arrived in South Wales this morning, on the London Paddington to Swansea train, to drum up support for Labour ahead of next month's Welsh Assembly elections.
He insisted he was taking the May 5 poll very seriously, issuing a broadside at the Conservatives for stifling the UK's economy.
He said: "We take nothing for granted and the elections don't count until it actually takes place. We know we have to fight for every vote.
"We are interested in who's going to be running the Welsh Assembly Government, who's going to be making the big decisions that matter for Wales.
"Carwyn has shown he's the best person to stand up for Wales and whether it's the policies he has on apprenticeships or police community support officers or tuition fees - he's making the right arguments.
"We've reached the right point (in terms of legislative powers) at this moment and I will be guided by the Labour Party in Wales and Carwyn with a view that they take on these issues.
"We are not calling for further powers at this point. But I will be guided by his decisions."
Labour are currently in a buoyant mood in Wales - with a recent poll putting the party on course to claim an overall majority in the national assembly.
Labour officials hope the campaign in Wales will act as a springboard for the UK general election in 2015 as they look to oust the Conservative-Liberal Democrat coalition from power.
But Welsh Tory leader Nick Bourne has repeatedly criticised Labour for failing Wales - saying parts of the principality were poorer than Eastern Europe and the left-of-centre party couldn't be trusted with the economy in Wales.
Mr Miliband hit back at the claims, attacking the Conservatives' approach on tackling the UK budget deficit via public sector spending cuts.
He said: "I don't agree with Mr Bourne. Growth was quite strong when the Conservatives came into office in Westminster.
"Because of the cuts, that are too far and too fast, they've destroyed consumer confidence.
"You're actually seeing growth having been set back. We look like we're going to have sluggish growth in our economy.
"That's not the right approach. People want an approach that prioritises jobs and growth as a route to cutting the deficit."
Following his journey in first class, Mr Miliband was met at Swansea railway station where he chatted with passers-by and posed for photographs with party members.
From there he travelled to Llanelli and is later due to arrive in Pembrokeshire where he is expected to give a speech at Pembroke Dock.
He will say: "A Labour-led assembly will not be able to stop the reckless deficit reduction plans of the Tories in Westminster."
Prior to his speech, Mr Miliband insisted that would not stop Labour from "standing up for Wales".
He added: "Labour is the party of hope, but the fact is that obviously the Welsh Assembly is having to deal with the block grant that it is being given and there are some cuts involved.
"But what Carwyn shows is that he is making a difference on things that matter - whether that's tuition fees or the NHS which is being undermined in England and he's upholding it here in Wales."
Doncaster MP Mr Miliband also criticised Welsh nationalists Plaid Cymru, who formed a coalition government with Labour following the last Assembly election in 2007.
He rejected Plaid's claims there was no longer a need for a Wales Office - saying the process "facilitated contact between the UK and Wales Governments" - as well as mocking Ieuan Wyn Jones' party for failing to make up its mind on whether it would do a deal with the Conservatives following the Assembly election.
He said: "Let's see what the results are, but we are not going to go into coalition with the Conservatives.
"Plaid haven't ruled that out. I don't think that's a great sign. You want to go into an election with a clear sense of what you're fighting for and who you are willing to work with.
"It says something about them that they're keeping so many options open."
He also repeated calls made by Labour that the UK Government's electrification of First Great Western train line should be extended as far west as Swansea.
He said: "It would be a tremendous boost to the local economy, and would send a strong signal to those looking to invest in Wales, that Swansea and West Wales is open for business.
"With the Tory-led Government cuts to Swansea-based public services such as the DVLA, there's now a stronger business case than ever to electrify the line to Swansea."
However, Labour's political rivals said Mr Miliband had failed to address why his party's control of the Assembly had left Wales's economy worse off.
Peter Black, Welsh Liberal Democrat candidate for South Wales West, said: "He could have come to Wales and explained how they spent so much money on economic development, but left Wales the poorest part of the UK.
"He could have proclaimed Labour's 'achievement' of ensuring Welsh patients wait longer than those in England or how proud he is that Welsh schools have slipped behind England and Scotland in results. Ed Miliband can only be ashamed of Labour's Welsh record."