Liberal Democrat leader Tim Farron has issued an appeal to Labour supporters to vote tactically and back his party to keep the Conservatives out.
In a direct message to Labour voters, Mr Farron said there were "dozens" of seats where only the Lib Dem could beat the Tory in the General Election on Thursday.
"If you live in one of those places, I need you to lend me your vote," he said.
"If you want a better deal on Europe, better funded schools and hospitals, and someone to stand up to Theresa May on the dementia tax and everything else, vote Liberal Democrat.
"In seats where only the Liberal Democrats can beat Labour, you can elect a Lib Dem MP to be your voice in Westminster, who will stand up for you, your job, your school and your hospital."
Mr Farron has insisted the Lib Dems would not enter into a coalition with Labour - or any other party - in the event of a hung parliament, despite Tory claims they would prop up Jeremy Corbyn in a "coalition of chaos" with the SNP.
The party went into the election with high hopes that, as the most pro-EU of the main parties, they could draw on support from among the 48% who voted Remain in last year's referendum to rebuild their Commons position following their drubbing in the 2015 election.
However the opinion polls suggest they have found it difficult to cut through to voters and may struggle to significantly increase their tally of just nine MPs in the last parliament.
Meanwhile Plaid Cymru leader Leanne Wood said her party would use its "leverage" in a hung parliament to boost investment in Wales.
"If neither Labour nor the Conservatives win a majority, Wales will be in a very strong position. Plaid Cymru MPs will use their votes to leverage the Welsh advantage," she said.
"We would use our votes to gain investment for Wales - electrification of our railways, a tidal lagoon and most importantly, a good Brexit deal for Wales."
Ms Wood, whose party had just three MPs in the last parliament, also sought to exploit divisions in the Labour ranks, accusing Welsh Labour MPs of preparing to knife their leader.
"People can't vote for Jeremy Corbyn in Wales. A vote for a Labour MP in Wales is most likely a vote to stab Corbyn in the back - who wants to give them a mandate to do that again?" she said.