Mr Johnson this week refused to rule out even tougher lockdown restrictions as hospitals come under growing strain from rising Covid-19 cases.
A travel ban on South America and Portugal came into effect on Friday morning, amid concern over a highly infectious new coronavirus variant from Brazil.
Mr Johnson has been coming under renewed pressure from Tory lockdown sceptics to set out how he will ease the restrictions on people’s liberties as cases come down.
Former minister Steve Baker – who co-ordinated opposition to Theresa May’s Brexit deal – suggested Mr Johnson’s leadership would be “on the table” if there was not a change of direction.
He urged colleagues on the Covid Recovery Group to make their views known to the chief whip, saying: “People are telling me they are losing faith in our Conservative Party leadership because they are not standing up for our values as a party.”