The 26-year-old Scot, who dominated the 2009 British Mini Cooper Championship with the Ellesmere Port-based Formula International team, was being groomed by the outfit to graduate to BTCC in 2011.
But yesterday the talented Scot was told Formula International would not continue into 2010 as a result of the financial downturn.
"Obviously it's not the way I wanted to start the year," Mortimer admitted, "but I have to thank the team for the support and the car they gave me last year to win the Mini title."
Mortimer — who has won every Scottish and British Mini championship he has entered in his first year — is now planning to switch to the inaugural British Trofeo Abarth 500 Championship.
The championship has been introduced as a low-cost series to the drivers. Each race car will owned by an Abarth dealer and then 'rented' to a driver. Scots car giant Arnold Clark will hold talks this week with Fiat regarding running an Abarth 500 race car.
"It's a fantastic opportunity to show people from some of the biggest teams just what I can do," Mortimer, whose car would be prepared by Edinburgh-based Tyncastle Garage, said.