Liberal Democrat leader Sir Vince Cable says his party is "beginning the fightback" after gaining dozens of seats in the English local elections.
"We are reasserting ourselves as a major national force," he told supporters in Richmond in London, where the party won control from the Tories.
It marks an improvement from the party's poor showing the last time the seats were contested in 2014.
The Lib Dems retained control in Cheltenham, Sutton and Eastleigh.
With about a third of councils still to declare - including Richmond's neighbouring borough of Kingston, another target - they had gained 40 seats - more than any other party.
Sir Vince also pointed to gained seats in Hull, Sunderland and Liverpool, claiming the pro-EU party was winning ground in both Leave and Remain-backing areas.
The Liberal Democrats have put a pledge of a referendum on the UK's final deal with the EU at the heart of their pitch to voters, hoping to gain Remain supporters alienated by the two largest parties' stance on Brexit.
But they have yet to recover the electoral ground lost after they joined the Conservatives in coalition government between 2010 and 2015.
"These things don't happen overnight," Sir Vince said.
"But I am absolutely certain that those people who wrote us off are now being proved to be completely wrong."
Polling expert Professor Sir John Curtice said the party had seen a sharper increase in vote share in areas with a large graduate population, saying it may be having "a measure of success" in reconnecting with that market.
Lib Dem home affairs spokesman Sir Ed Davey said it was a "great night" and a "sign of things to come".
He told BBC Radio 4's Today programme voters were "desperate" for a party that was neither "right wing Brexit Tory" or "left wing Corbynista".