Businesses will be "funding their own funeral" if they continue to donate to the Conservative Party that backs a "disastrous hard Brexit", Tim Farron will say.
Mr Farron will urge firms to "dump the Tories" and pitch the Liberal Democrats as the "new party of business" because it is committed to keeping the UK in the single market.
The Lib Dems want a second referendum on the final Brexit deal and have described Theresa May's commitment to taking the UK out of the single market to get control over immigration as a "disaster".
Labour has made clear it will not back a second referendum and accepts that the free movement of EU citizens cannot continue.
On a visit to Tory-held St Albans, Mr Farron will say: "My message to business is this – dump the Tories.
"Every penny you give them will hurt you; you are funding your own funeral."
He will go on: "With this disastrous hard Brexit the Government is hurting businesses, both big and small, costing jobs and hitting families. All this means fewer jobs, higher prices and spiralling costs of things like fuel. This is a Brexit squeeze affecting millions of people.
"I say, clearly, to businesses, you must come and back the Liberal Democrats – this is not a moment for hiding and hoping things change. You need to desert the Tories.
"The single market matters – it's vital to our economy.
"This election is a chance to change Britain's future.
"While the Tories run headlong towards a hard Brexit and Labour cheers them on, only the Liberal Democrats are standing up for a Britain that is open, tolerant and united."