Theresa May will use a European Union meeting later this month to make the case for her “Chequers plan” for Brexit direct to fellow leaders.
The plan has come under assault from many sides, with the EU’s chief negotiator Michel Barnier saying he is “strongly opposed” to the UK proposals, which he warned would undermine the European project and the single market.
But the Prime Minister’s official spokesman noted that, while negotiations are taking place with Mr Barnier as the representative of the European Commission, final approval of any Brexit deal is a matter for EU leaders meeting in the European Council.
Downing Street declined to comment on a damning report by EU ombudsman Emily O’Reilly on the fast-track appointment of Martin Selmayr as the commission’s top civil servant.
Formerly chief of staff to commission president Jean-Claude Juncker, the German bureaucrat was unexpectedly named secretary-general in February.
In her report, Ms O’Reilly identified four counts of maladministration by the commission in the process.
Number 10 said it was “a matter for the commission”.
The Prime Minister will join counterparts from the remaining 27 EU nations for an informal session of the council in Austrian city Salzburg on September 20.
Her spokesman confirmed that she would use the opportunity to engage with individual leaders on the Brexit issue.
“The negotiations are taking place with the commission, we have always respected that fact,” said the PM’s spokesman.
“But equally this is a decision which at the end of the process will be taken at a political level by the European Council.
“So you can obviously expect a continued and strong engagement with fellow European countries.”
He added: “You have seen a lot of personal involvement from the Prime Minister in terms of the meetings she has held with all of her various counterparts and at the various summits which we have been attending recently.
“We have Salzburg coming up and that will obviously be an opportunity for further engagement between the PM and the 27.”
Brexit Secretary Dominic Raab told ministers at Tuesday’s Cabinet meeting that the Chequers proposals had received a “warm and positive” response from European leaders over the summer.
The Commons resumed after the summer recess, with the pace of Brexit talks in Brussels intensifying in the hope of achieving a deal this autumn.
But Conservative divisions have deepened, with former foreign secretary Boris Johnson and Mrs May’s Downing Street engaged in a bitter war of words over the approach to Brexit.
Mr Johnson used his regular Daily Telegraph column on Monday to launch a scathing attack on Mrs May’s Brexit strategy, branding it a “fix” that can only lead to victory for the EU.
But Downing Street said the former Cabinet minister was offering “no new ideas” and said the country needed “serious leadership with a serious plan”, which was being provided by the current premier.
Former party leader Lord Hague used his own Telegraph column to warn Tories their civil war could result in the collapse of the Government and either a second referendum or a general election – and the possibility of Jeremy Corbyn in Downing Street.
“Some say May’s plan is too much of a compromise, a small number that it isn’t enough of one, and still others now advocate a different compromise altogether,” he said.
“The likely result is so obvious it hardly needs stating, which is that the entire idea is put at risk, and all of them will lose out in the end.
“It is thus quite possible that a year from now, we could be contemplating why we are still in the EU after all, or why we left it with maximum damage all round with minimum notice, or how we came to have an even weaker minority government, or how a Marxist despised by his own MPs ended up as Prime Minister.”
Meanwhile the pro-EU Best for Britain campaign group launched a new £200,000 push for a second referendum on the terms of the Brexit deal.