The Lib Dems have drafted a manifesto for the European elections and party members will start picking MEP candidates in the coming days.
The pro-EU party will promise to spend the money earmarked for Brexit to instead “regenerate” the country.
With the prospect of a lengthy delay to Brexit requiring the UK to hold the elections that start on May 23, the Lib Dems said they were “raring to go”.
The party currently has just one MEP – having lost 10 seats at the last poll in 2014.
But it will hope this year’s elections, held amid chaos in Westminster over Brexit, would see it benefit from a surge of support from pro-EU voters.
Theresa May has said she still wants to get a deal approved by parliament by May 22, in order to avoid the UK having to hold the elections three years after the vote to Leave.
But speaking during prime minister’s questions on Wednesday, the PM did not rule it out.
Tory MP Nigel Evans had demanded May say “no, no, no” to the UK taking part.
Tom Brake, the Lib Dem Brexit spokesperson, said the party’s manifesto would “set our vision for the UK inside the EU”.
“We have been fighting tooth and nail not just to keep the UK in the EU, but for the UK to be a leader in the EU,” he said.
“Just imagine what we could achieve if Brexit was stopped, not least using the billions earmarked for Brexit to instead regenerate the towns, cities and communities in the greatest need.
“We will be ready to go to the polls with a clear offer; every Liberal Democrat elected is another voice fighting for our country’s place in the European Union.”
Vince Cable has said he will step down after the local elections on May 2, meaning the party could fight the European poll under a new leader.
May is due to hold talks with Jeremy Corbyn on Wednesday afternoon in an attempt to break the Brexit deadlock in parliament.
The move has triggered an angry backlash from Tory MPs, who fear she will accept a soft exit from the the EU.