LONDON (REUTERS) - British Prime Minister Boris Johnson met his Brexiteer-dominated team of senior ministers for the first time on Thursday (July 25) to plot how to persuade the European Union to agree to a new Brexit deal ahead of the Halloween exit deadline.

Johnson told his new top team of ministers on Thursday they had a momentous task ahead and were committed to delivering Brexit by Oct 31.

"We have a momentous task ahead of us. At a pivotal moment in our country's history we are now committed, all of us, to leaving the European Union on October 31 or indeed earlier, no ifs, no buts," he said at the start of the meeting, television footage showed.

Mr Johnson's dramatic rise to Britain's top job sets the world's fifth-largest economy up for a showdown with the EU and a potential constitutional crisis - or election - at home, as lawmakers have vowed to thwart a no-deal Brexit.

Britain's new leader promised to do a new Brexit deal with the bloc within less than 99 days, but warned that if EU leaders refused - what he termed a "remote possibility" - then Britain would leave without a deal, "no ifs or buts".

"I am convinced that we can do a deal," Mr Johnson, 55, said on arrival at No. 10 Downing Street, the premier's official residence, after meeting Queen Elizabeth, who requested he form a government.

Mr Johnson's bet is that the threat of a no-deal Brexit will persuade the EU's biggest powers - Germany and France - to agree to revise the divorce deal that former prime minister Theresa May agreed last November but failed to ratify.

The EU has so far repeatedly refused to countenance rewriting the Withdrawal Agreement part of the divorce deal, but has said it could change the so called "Political Declaration"on future ties.

The bloc has congratulated Mr Johnson on his victory but was firm that it would not offer Britain better departure terms.

SWEEPING CULL

Mr Johnson, who sported a sometimes shambolic persona in his rise to power, showed mettle in office, sweeping away his predecessor's government in one of the biggest culls of senior government jobs in recent British history.

"Night of the Blond Knives", said The Sun, Britain's most-read newspaper, in reference to the colour of Mr Johnson's dishevelled mop of hair.

A total of 17 ministers in Mrs May's government either resigned or were sacked, creating a powerful new group of enemies in Parliament.

Most of Mr Johnson's senior appointees are Brexit supporters.

Mr Sajid Javid, 49, was named as his finance minister. He is a eurosceptic who voted to remain in the 2016 referendum.

Others are avowed Brexiteers: Ms Priti Patel was appointed interior minister, Mr Dominic Raab was appointed foreign minister and Mr Stephen Barclay remained as Brexit minister.

Mr Johnson also appointed Mr Dominic Cummings, the campaign director of the official Brexit Vote Leave campaign, as a senior adviser in Downing Street.