Irish premier, after a one-hour call with Johnson, said the Brexit deal wouldn’t be renegotiated.
"We will be ready to come out on Oct 31 — deal or no deal," Johnson tells reporters in Truro, southwest England.
British premier will meet German chancellor and French president in coming week, Downing Street says.
Sunday Times publishes what it says are confidential government memos outlining consequences of tearing up May's deal.
Johnson alleges that anti-Brexit UK politicians are collaborating with the EU to block Britain’s exit from the bloc.
The decline is set to raise alarm that the economy could experience its first recession in a decade.
Year-on-year economic growth slid to 1.2pc from 1.8pc in the first quarter, its weakest since the start of 2018.
London insists Brussels must renegotiate key elements of the divorce deal struck last year.
There is an increased chance that Britain will crash out of the EU in October.
Boris Johnson's candidate was edged out by a pro-EU rival in a by-election that slims his parliamentary majority to one.
The pound has lost 3.6 cents since Johnson was named Britain's new prime minister a week ago.
Countries outside the bloc do not necessarily have market access even if their rules were equivalent.
UK PM Boris Johnson has promised to deliver Brexit by end of October "no ifs or buts".
Johnson promises to step up negotiations on post-Brexit trade deals and set up free ports to boost the economy.
Sterling slips 0.1 per cent to $1.2437, below its weekly high of $1.2522.
On entering Downing Street on Wednesday, Johnson set up a showdown with the EU.
He will inherit a political crisis over Britain’s exit from European Union, currently due to take place on October 31.
Here are some of the most contentious episodes in the life of the bombastic 55-year-old former foreign secretary.
The measure, which passed by 315 votes to 274, is a major setback for former London mayor Boris Johnson.
"If they come and ask us to renegotiate the Brexit deal, we will say ‘Thanks, but no thanks’," says an EU diplomat.
The three-year Brexit crisis could be about to deepen.
Hot favourite Boris Johnson faces foreign minister Jeremy Hunt in a run-off vote.
Both Johnson and Hunt have promised to take Britain out of the EU as quickly as possible.
The Brexit-backing former foreign minister picked up 114 of the 313 votes cast in a secret ballot in the lower House.
Churchill is buried too deep to feel the pain that comes from an empire revenging itself.
Brussels says it won't enter talks on future trade until the UK honours financial obligations it made as a member state.
Hunt says he spoke to German Chancellor Angela Merkel at this week’s D-Day commemorations.
May pledged to fight “burning injustices”, but made little headway as her premiership became dominated by Brexit.
11 Conservative MPs, including Boris Johnson, vying for post but expected to drop out before nomination deadline.
Boris Johnson is accused of misleading public regarding cost of Britain's EU membership during his Brexit campaign.