European elections are a chance to draw a line under “grief” over the current “lack of leadership in politics”, Plaid Cymru’s leader has said.
Launching the party’s campaign, Adam Price urged anyone in Wales wanting another EU poll to back Plaid Cymru.
He said the party was targeting Welsh Labour voters who felt let down on Brexit.
Plaid was the only Welsh party “with a chance of winning seats” unequivocally backing a further referendum, he said.
Plaid says Wales should hold an independence referendum if Brexit occurs without a further EU referendum.
At the Plaid Cymru campaign launch for the European election in Cardiff on Thursday, Mr Price said thousand of Labour supporters across Wales were living in a “state of permanent despair”.
European elections, on 23 May, offered a chance to draw a line “under your grief” over the “lack of leadership in politics in general at the moment”, he said.
“These elections are a bridge across which thousands of people can venture to make the change that Wales needs,” he said.
“If we want a European future for Wales we have to vote for Plaid Cymru – the only party that unequivocally in that future.”
A vote for Plaid Cymru was “our chance” to “make Wales matter in Europe and the world” he said.
“We know that Wales matters. Wales matters to millions of our people, in their daily lives. But in the corridors of power in Westminster it doesn’t matter one bit.
“This election is not just about putting Wales – our lives, our problems and our dreams – at the heart of Europe, but bringing in Wales from the margins, out from the cold.”
Plaid has previously said that a cross-party deal between anti-Brexit parties “could have been an opportunity to offer the voters the clearest possible choice at the ballot box” and blamed the Greens in Wales for the two parties failing to work together in the European election.
The Green Party has said no approach had been made to it by other parties.
In the last European Parliament election in 2014, the four Welsh seats were split between Plaid, Labour, UKIP and the Conservatives.
Mr Price said: “We are the only party in Wales with a chance of winning seats in the European Parliament that is unequivocally supporting a People’s Vote.
“For that reason we are appealing for support across the parties. We are saying to progressive people across the political spectrum – join us.
“Our appeal is especially to [Welsh] Labour supporters who, for years, have been in a state of permanent disappointment with the leadership of their party.”
Plaid Cymru’s lead candidate, Jill Evans, first elected an MEP in 1999, said she was “proud and thankful” to be standing for a fifth time.
“Because now, more than ever, Wales needs a voice in Europe and because there is so much potential to build a better future for our nation in Europe.”
“We are the only realistic choice for voters who are looking for a different and a constructive way forward,” she added.
The European Parliament elections in Wales
There are eight parties fighting for four Welsh seats in the planned European elections on 23 May.
Welsh Labour, the Welsh Conservatives, Plaid Cymru, the Welsh Liberal Democrats, UKIP and the Green Party are joined by Change UK and the Brexit Party.