The tension was revealed last week when the Foreign Office’s Twitter account ‘liked’ a post from Labor MP Zara Sultana which described former Home Secretary Priti Patel as ‘unspeakably cruel’.
Ms Patel said: ‘It shows that I have faced enormous resistance from the Foreign Office in my efforts to secure the vote of the British people.
An ally of Ms Truss said it reflected the ‘absolute hurdle’ Ms Patel faced, although the Foreign Office insisted it was a ‘genuine mistake’ of a staff member.
But the ally said the Foreign Ministry is “reversing” Rwanda’s immigration policy at every turn. There have been calls for Ms Truss to challenge ‘Sir Humphreys’ – named after the obstructive mandarin from sitcom ‘Yes Minister’.
Adding to the appeals, a former minister said: ‘The underperforming ‘blob’ in Whitehall is what is really holding this country back.
“We should have an annual shuffle of permanent secretaries and make the honors system more performance-based.”
A prominent Tory backbench MP feared efforts to undermine politics were escalating, saying: ‘If they think they’re going to get rid of us in the next election, it’s only going to get worse, won’t is this not ?
Toby Young, founder of the Free Speech Coalition, said, “Permanent secretaries are their own laws, pursuing their own sober agendas…The solution is to make political appointees to senior civil servants, as is done in the United States .
Tory MP Craig Mackinlay said: ‘The impact of resistance to change has prevailed and the Brexit dividend has not been enough… A Truss government could bring fresh thinking to tackle long-term issues integrated.”
However, a former minister said it was “difficult to single out resistance from the left”, adding that it was “more a matter of risk aversion and attachment to the status quo”.
The First Division Association of the Civil Service Union declined to comment.