Scottish Lib Dem leader Willie Rennie has accused the Conservatives of undoing the coalition’s good work “within three hours”.
He also said the Tories could no longer call themselves unionist after a general election campaign “designed to enflame anti-Scottish sentiment”.
Mr Rennie also described the depiction of Alex Salmond as a pickpocket as “disgusting”.
“They decided to put their party before the country,” he said.
“The good work they did with us in government was undone within three hours.”
To “undo some of the damage”, the Tories now need to deliver on the vow and Smith Commission in full, he added.
He also warned the “strings” within English Votes for English Laws – such as the veto – need to go.
He went on: “Then they need to go further and embrace a wider reform agenda.
“Our answer is federalism. We want to light the fires of federalism.
“We need to look at the rest of the UK for reform. That way we can create a sustainable settlement.”
He said he did not hold out any hope that the Conservatives would heed his advice, but added: “If they really want to settle down the constitution, these are the things they need to do.”
Mr Rennie made the remarks ahead of his conference speech in which he will set out his party’s campaign for next year’s Scottish Parliament elections.
He is expected to say: “Unlike those who are veering to the left or right we are sticking to the radical, liberal, centre ground.
“We say power is safer when it is shared and will trust communities and individuals with the power to control their own lives – putting an end to the Holyrood-knows-best mentality.”