Lib Dems would make voting reform a red line in any deal to prop up Labour after the next election, the Mirror understands.
The party, still scarred by five years of coalition government with the Tories, would rule out a formal pact with Keir Starmer ’s party if the next election delivered another hung Parliament.
But the Lib Dems could offer support on certain legislation - in return for an overhaul of the voting system that could keep the Conservatives out of power forever.
While Labour is riding high in the polls and on course for an overall majority, many Labour MPs and insiders fear the lead is overstated - and they could end up relying on other parties to force through laws after the next general election, due by January 11, 2025.
The Lib Dems would demand a shake-up of the electoral system - and, unlike in 2011, it is thought the party would insist the measure should not be put to a referendum.
The party was left humiliated 11 years ago when electors rejected plans for an alternative vote (AV) system by 67.9% to 32.1% - with just two in five people bothering to cast a ballot.
Multiple sources the Mirror has spoken to say next time, the Lib Dems would demand full proportional representation rather than AV - and call for the change without offering a referendum.
Speaking exclusively to the Mirror, Sir Ed Davey - a Cabinet Minister under the coalition government - said: “I’m going to put it (PR) in our Liberal Democrat manifesto, and if people vote for Liberal Democrat policies they will get Liberal Democrat policies - that’s how elections work.”
He also signalled his opposition to suggestions AV could be the system put forward again, saying “that type of change” would not be on offer.
“ Liberal Democrats want proportional representation, we want fair representation because that’s the way to give voters more power, and that's the sort of reform we want to see,” he said.
“Voters have never had a chance - besides voting Liberal Democrat, and we want more and more people to vote Liberal Democrat - so they have the chance to back what I would call proper fair votes.”
While insisting it would be “absolutely wrong to start thinking about what’s going to happen after the next election”, he insisted the Lib Dems would not do another deal with the Tories.
“We will never support the Conservatives but we will look at a whole range of issues,” he said.
“For me, obviously sorting out people’s cost of living is very important, sorting out the NHS is incredibly important and public services more broadly - and reforming our political system is very, very important.
“The Conservatives have abused the current political system and it doesn't represent voters.
“We want to put power in voters’ hands, we want to make sure that governments are more accountable to them and that’s why we want political reform.”
He also said voters were clever enough to decide who to cast ballots for in which seats if their priority was ousting the Tories.
Denying a pact with Labour to carve up the electoral map where the parties would campaign hard or softly depending on who was more likely to win, he insisted: “There have been no deals, there are no deals, there will be no deals.
“Voters can work out for themselves when it is the Liberal Democrats who can beat the Conservatives - and they do that.”
