The Lib Dem pledge to scrap the Severn tolls will make sure future control of the bridges will be an election issue in 2015.
The Welsh Government has said it was 'good to hear' a UK minister back proposals that include devolving 'significant' income tax powers.
A poll for ITV Wales points to an overall Labour in the Assembly and puts UKIP on course to win seats in the Senedd.
Welsh Liberal Democrat Leader Kirsty Williams has dismissed calls for the Severn tolls to be devolved to the Welsh Government, saying it would be better for Wales to abolish them altogether.
The First Minister has previously called for responsibility for the tolls and their income to be transferred and, in response to the Lib Dem pledge, the Welsh Government has said it should 'have a say'when the bridges return to public ownership.
But Kirsty Williams says no UK Government is likely to agree to such a move.
Welsh Liberal Democrat leader Kirsty Williams says scrapping the tolls on the Severn Bridges would cost the UK Government around £15m a year once the construction bill is paid in 2018 and debts associated with the bridges are settled.
The Welsh Government says it has 'made clear' to the UK Government that Wales should have a say on the future of the Severn Bridge tolls.
– Welsh Government spokesperson
The Department of Transport and the Highway Agency is currently responsible for both crossings, including the level of the tolls.
However, we have made it clear to the UK Government that we should have a say on future of the tolls after the end of the current concession agreement with Severn River Crossing PLC.
The Welsh Liberal Democrats say they are 'delighted' that the party has pledged to scrap Severn Bridge tolls.
– Kirsty Williams, leader of the Welsh Liberal Democrats
We are the only party that will completely scrap the unfair Severn Bridge tolls.
This announcement will offer a huge boost to the Welsh economy and save the average commuter around £1,536 a year. It will help to build a strong economy and a fairer society.
These tolls shouldn’t be used as a money-maker by either the Welsh or UK Government. Tolls are extremely rare in the UK, so I see no reason why people should be forced to pay to enter Wales.
The Liberal Democrats have pledged to scrap the Severn Bridge tolls if the party is successful in the forthcoming General Election.
The commitment will be outlined in the party's ‘pre-manifesto’ in September.
The Severn Crossings are managed by a private concessionaire, which is due to end when enough revenue target is collected from tolls - predicted to be sometime in 2018.
Once the bridges are transferred into public ownership and debts are repaid, the Liberal Democrats say they will abolish the tolls.
Cardiff Central MP Jenny Willott will become the first Liberal Democrat woman to sit at the cabinet table today.
Although she does not have full cabinet minister rank, the 39 year old will take her seat alongside new women's minister, Tory MP Nicky Morgan, to make a presentation on coalition efforts to close the gender pay gap.
In her new role, Ms Willott will promote more family-friendly workplaces and tackle issues around discrimination. She will attend cabinet when issues related to shared parental leave and workplace rights are on the agenda.
Ms Willott said: "This is a really exciting opportunity to tackle an issue I'm passionate about at the very heart of government.
"I'm looking forward to sitting around the cabinet table to promote longstanding Liberal Democrat priorities such as making workplaces more family-friendly and closing the gender pay gap."
Welsh Liberal Democrat leader Kirsty Williams has been speaking on the second day of her party's conference in Newport.
.@kirsty_williams : 'This is a great nation of ours...too often let down by a Welsh Govt which fails ...time and time again.'
.@kirsty_williams 'How dare (Carwyn Jones) hide behind the people he's meant to lead. What kind of leader does that?'
.@kirsty_williams :First Minister shd have kept talking re: rail electrification funding but 'he just wanted the row in the media after all'
Welsh Labour has attacked the Welsh Liberal Democrats ahead of a speech in which the party's leader Kirsty Williams is expected to criticise the First Minister for his oversight of public services in Wales. A Labour spokesperson said,
– Welsh Labour spokesperson
Nick Clegg's Liberal Democrats are a growing irrelevance in Wales. They are shouting louder and louder to try and fill smaller and emptier conference halls.
If Kirsty Williams wanted to make Liberals relevant again she could start by demanding an end to the Tory war on Wales. Instead the Libs seem to be saddling up alongside Westminster coalition partners to denigrate the public sector in Wales, using the same bogus arguments and dodgy statistics for political gain. And they have failed miserably to support Wales on rail electrification.
Welsh Liberal Democrat delegates discuss conference issues with Political Editor Adrian Masters. Jane Dodds is the party's parliamentary candidate for 2015 in Montgomeryshire. Alec Dauncey is the Lib Dems' lead candidate in May's European Parliament election.