The chairman of the campaign for a Yes vote in March's referendum on further powers for the Welsh assembly says he believes it will create a "no excuses culture" for Welsh politics.
Roger Lewis was speaking at the official launch of "Yes for Wales" in Cardiff.
The cross-party campaign group is backing further law-making powers for Wales.
The No campaign has yet to launch and is being led by True Wales.
Mr Lewis said people from across the country were coming together to support what he called "a simple principle" - that laws affecting only Wales should be made in Wales.
At present, the assembly can only pass Welsh laws if the UK Parliament grants it the powers in specific devolved areas - a process which can take months or even years.
A Yes vote in a referendum would enable the assembly to have law-making powers across all devolved areas without reference to Westminster, whereas a No vote would mean the piece-by-piece system would continue.
Mr Lewis, who is also chief executive of the Welsh Rugby Union, said that if given what he called "the tools to do the job", Welsh politicians would not be able to hide behind the way laws are made as an excuse for not delivering for the people of Wales.
He said: "Time, money, energy and imagination are being exhausted on making an over-complicated law-making system work.
"In times like this we cannot afford to waste a moment continually arguing about the way laws are made.
"It is time for the assembly to be given the tools necessary to get on with the job it was elected to, so that all our energies can be focused on forging a better future."
Mr Lewis would not be drawn on what he believed would be a satisfactory turnout in the poll - recent opinion polls have pointed to a turnout of around 35 to 40%.
He admitted that the Yes For Wales group would be "walking a tightrope" as far as politicising the campaign was concerned, with assembly elections due in May, just weeks after the referendum.
Its campaign leaflet refers to the assembly protecting "schools, skills and hospitals" during the squeeze on public finances - a phrase used repeatedly by Labour and Plaid Cymru ministers in discussing their recent budget.
True Wales, the group which will campaign for a No vote in the referendum due to be held on 3 March, is expected to launch its campaign in the next couple of weeks.
A spokeswoman criticised the Yes campaign's decision to host the launch at the University of Glamorgan, saying the assembly was guilty of "long-term chronic underfunding" of higher education.
"Politicians are asking the people of Wales to give them more powers as a vote of confidence, but why should the latter have any confidence in a government with the current educational spending record?" she said.
"How can our country's economy flourish if its successive governments short-change our children's future by chronic under-investment in our schools and universities?"