THE PRIME Minister has failed to defend the leader of the Scottish Conservatives when challenged in the Commons. 

Boris Johnson was asked outright if he supported comments by a senior Tory that Douglas Ross was a "lightweight".

However the PM noticeably did not address the comments, made by Jacob Rees-Mogg, directly  but instead praised the work of the Scottish Conservatives as a whole. 

Asked by Labour MP Stephen Kinnock if he agreed "with the Leader of the House that the leader of Scottish Conservatives is a lightweight", Mr Johnson responded with an answer about the union. 

READ MORE: Rees-Mogg brands Douglas Ross 'lightweight figure

He said: "The Conservative approach to the union is one that I think is right for our country. We want to keep it together and I think Conservatives in Scotland do an excellent job.

"Their stout defence of the union was repaid in the last election, and Labour is increasingly endangering the union." 

The tension between Mr Johnson and the Scottish Conservatives has been growing since last week when Douglas Ross became the first Tory MP to call for him to resign. 

The Herald: Jacob Rees-Mogg

This prompted Mr Rees-Mogg to attack Mr Ross on Newsnight, describing the Scottish Tory leader as a "lightweight figure", raising eyebrows among the Scottish party as well as the wider Westminster group. 

All 31 Scottish Tory MSPs have been reported to have backed Mr Ross's call for the the Prime Minsiter's resignation, with some going so far as to suggest they should split from the UK party and become a separate entity. 

This has been dismissed by several senior Scottish Conservative sources when asked by The Herald.