Speaking at the opening of of the Scottish Conservative party's spring conference in Edinburgh, the prime minister is expected to say the referendum is "a major life decision" that shouldn't be made without knowing the full consequences.
He is expected to add:
And look at who's laying out those consequences: the governor of the Bank of England, the president of the European Commission, business chiefs from companies like BP and Shell; Alliance Trust and RBS; Lloyds, Barclays - the list goes on.
These are not political puppets, they are serious, non-partisan figures.
So, the idea that these are empty warnings and political scare-mongering is a myth - and we owe it to the people of Scotland to take that myth apart.
More top news
The success of the No camp is mainly due to Tsipras convincing people a No vote will strengthen their hands in negotiations.
As we move into the weekend, expect things to get rather more unsettled weather-wise - thought it will stay hot and humid for some.
More than 80 prominent Britons, including Boris Johnson, Russell Brand and former Government ministers, urge Obama to release Aamer.