London -- The next chapter of British politics opened with a bold pledge by an incoming prime minister: "Dude, we are going to energize the country, we are going to get Brexit done." Boris Johnson has always had a knack for striking a chord, but as he prepared to meet Queen Elizabeth on Tuesday and officially take the reins of power, it was unclear how far his "new spirit of can-do" would carry the U.K. through its most tumultuous period in decades.

Johnson has a reputation for changing his tune to suit the political winds, but his consistent (at least recently) pledge to pull Britain out of the European Union on Oct. 31 as scheduled -- with or without an agreement on the terms of that divorce -- won him the support of his Conservative Party's core and a stay in the prime minister's official residence at 10 Downing Street. Few people expect him to be there for long.

The problem Johnson faces is the same one that forced his predecessor, Theresa May, to officially step down on Wednesday; Britain's lawmakers cannot agree on how (or if) the U.K. should leave the EU.

Get Breaking News Delivered to Your Inbox

The Conservative Party gave the public a say with the referendum in 2016 and the public voted to leave, but it was a non-binding vote. The leading Conservatives vowed to deliver and make Brexit a reality, and May's government spent two years negotiating a deal to do so with the Europeans. But Parliament rejected that deal repeatedly, leaving her defeated, and departing.

Johnson has vowed to either negotiate a new divorce deal with Europe that is more favorable to the U.K., or carry on with a "no-deal" Brexit by the current Oct. 31 deadline for withdrawal. The EU has made it clear that negotiations will not be reopened, however, so it's unclear how the new PM can offer the prospect of a new deal.

The no-deal option is so unpopular in Parliament that lawmakers are expected to block Johnson from letting it happen. It is widely expected that the opposition Labour Party will call a no-confidence vote on Johnson in Parliament, which could result in new national elections. That would force the Conservatives to defend their leadership role, and could feel a lot like a new vote on the concept of Brexit itself.

Boris Johnson becomes

Outgoing Prime Minister May began her last day on the job on the floor of Parliament, with her final rhetorical joust with opponents at the Wednesday ritual of Prime Minister's Questions. She was lambasted anew by her foes, and lauded for noble efforts by many in her own party.

She then headed for the last time to 10 Downing Street as its official occupant. After saying farewell to staff and colleagues, May stepped out to the same podium from which she tearfully announced her decision to resign just two months ago.

May didn't linger. She thanked her staff and colleagues, her husband and the nation at large for "putting your faith in me and giving me the chance to serve." The outgoing PM said she looked forward to returning to Parliament as a lawmaker, to "play my part in making our United Kingdom a great country with a great future, a country that truly works for everyone."

May then made the short trip to Buckingham Palace and formally tendered her resignation to Queen Elizabeth II, and recommend that the queen accept Johnson as her replacement.

Not long after she left, Johnson showed up at the palace to meet the monarch himself. His car ride to Buckingham Palace was very briefly delayed by a small group of Greenpeace protesters, who ran out into the road to block his vehicle convoy. The protesters were quickly pushed aside by police and Johnson's Jaguar made it to the monarch's official London residence.

Queen Elizabeth II welcomes newly elected leader of the Conservative party Boris Johnson during an audience in Buckingham Palace, London, where she invited him to become Prime Minister and form a new government. PA/Victoria Jones

It's largely a formality of the British democracy, but the queen officially asked Johnson, as the head of the leading party in Parliament, to form a new government. With that, he became the prime minister.

Johnson headed straight to his new residence at 10 Downing Street and didn't even go inside before stepping up to the podium that May left hours earlier to address his country and the world. He was defiant, vowing to "fulfil the repeated promises of parliament to the people and come out of the EU on October 31, no ifs or buts."

He said he would strike a "new deal, a better deal" with the Europeans based on free trade, in spite of the bloc's insistence that there would be no re-negotiations. He didn't give any new detail, however, on how he planned to make good on his grand promises.

Johnson stressed that his government would be "fully determined, at last, to take advantage of Brexit," but said his government would ensure the United Kingdom was prepared for a no-deal exit from the European Union, should it come to that.

"To all those who continue to prophesize disaster," Johnson said, "do not under estimate this country."