Sir Vince Cable will hail the Liberal Democrats as the "secret phenomenon in British politics" as he launches the party's local elections campaign.
The party's leader will put housing and education at the heart of his pitch ahead of next month's polls.
The Lib Dems have consistently polled in single figures since the turn of the year.
Former leader Sir Nick Clegg got 13% in the 2014 elections, while there has been speculation that Lib Dem-controlled Sutton council could be vulnerable.
But launching his party's campaign in Watford, Sir Vince is expected to say: "There is a secret phenomenon in British politics.
"It is occurring in by-elections all over the country, week in, week out, to local authorities from Sunderland to Somerset.
"Against the Tories. Against Labour. In Leave areas. In Remain areas.
"Since the general election in 2017, the Liberal Democrats are up 15 seats, double Labour's increase of seven, while the Conservatives are tanking - they have lost 18 seats.
"These real votes in real ballot boxes show Liberal Democrat support at double our national opinion poll rating.
"What we're showing is that where Liberal Democrats come out fighting, Liberal Democrats can win."
The former business secretary is set to highlight schools funding as the biggest issue on the doorsteps in his Richmond constituency.
He will say the issue highlights the difference between the coalition and "the hard-right Conservative Governments which have followed".
Sir Vince will say May's elections "are a chance for parents and teachers to send a signal to the Government on schools".
He will also compare Lib Dem councils' record on housing to authorities run by the Tories and Labour, saying councils under Lib Dem control have stood up to developers and lent money to housing associations.
"So support for the Liberal Democrats is support for new homes, support for curtailing the right to buy where there isn't a guaranteed 100% replacement of stock sold off, and support for tough measures on empty property, used by investors as modern-day pots of gold, when they should be available for families to live in," he is expected to say.