The European Research Group (ERG) of Conservatives will not formally endorse either Rishi Sunak or Penny Mordaunt for the party leadership.
In a statement, ERG chairman Mark Francois said: “We believe that we have one – and potentially two – extremely strong options to be leader of the Conservative Party but as a group we were unable to collectively endorse either candidate.
“However, some of us having spoken to both potential candidates this morning, they were equally adamant that they would take – if they became prime minister – a very robust line on the Northern Ireland Protocol, up to and including, if necessary, utilising the Parliament Act to ensure that the Northern Ireland Protocol Bill reaches the statute book.”
It comes as Ms Mordaunt is desperately battling for support from Tory MPs to prevent Mr Sunak being installed as prime minister without a vote of the party membership after Boris Johnson scrapped his comeback bid.
ERG chairman Mark Francois POOL
Rishi Sunak is the firm frontrunner as he commands the public support of around half the parliamentary party Jacob King
Mr Sunak, a former chancellor, is the firm frontrunner as he commands the public support of around half the parliamentary party – far more than the 100 nominations needed by the 2pm deadline.
With a little over two hours to spare, Ms Mordaunt’s campaign claimed to have received the support of at least 90 Conservative MPs and urged others to back her so party members can have their say in an online ballot.
The Commons Leader would face Mr Sunak in an online ballot if she reaches the threshold on Monday, but if she fails then her rival will succeed Liz Truss as the Tory leader in a “coronation”.
A Government source said Mr Sunak, who lost to Ms Truss in the last contest just seven weeks ago, could become prime minister later in the day if he becomes the only candidate, though Tuesday is seen as more likely.
Ms Mordaunt’s campaign allies insisted they were “confident” she would reach the threshold and claimed she had a far higher tally than the around 26 declarations of support that have been made public.
A campaign source said: “We have now passed 90. For the sake of the party, it’s important our members have their say.”
The pound, after a torrid time under Ms Truss, continued to rise and the gilt market cooled, making it cheaper for the Government to borrow money, as Mr Sunak edged towards No 10.