By Kylie MacLellan and Michael Holden

LONDON (Reuters) - Justice Secretary Michael Gove pitched on Friday to be the prime minister to take Britain out of the EU, a day after he destroyed the chances of another frontrunner in what some colleagues called an act of treachery.

Gove's decision on Thursday to throw his hat in the ring to replace David Cameron, who is standing down after Britons voted to leave the European Union last week, upturned British politics after he had previously said he would back Boris Johnson.

His comment that Johnson, with whom he had campaigned across the country to secure the vote for Brexit, was not fit to lead effectively ended the popular former London mayor's hopes.

Five candidates are now hoping to replace Cameron, with interior minister Theresa May the favorite with bookmakers. Ruling Conservative Party lawmakers will whittle the field down to two, before a final decision is made by party members with the new leader in place in early September.

The decision to quit the EU has cost Britain its top credit rating, pushed the pound to its lowest level against the dollar since the mid-1980s and wiped a record $3 trillion off global shares. EU leaders are scrambling to prevent further unraveling of a bloc that helped guarantee peace in post-war Europe.

"I have to say I never thought I'd ever be in this position. I did not want it, indeed I did almost everything not to be a candidate for the leadership of this party," Gove said in a speech in central London as he launched his campaign.

Colleagues in the ruling Conservative Party who backed Johnson have poured oppobrium on Gove. Johnson himself hinted he saw it as treason, hiding a quote from Shakespeare's play about political murder, "Julius Caesar", in his speech announcing his decision not to stand on Thursday.

Britain's biggest-selling tabloid the Sun said Johnson had been "Brexecuted".

"There is a very deep pit reserved in Hell for such as he. #Gove", Conservative lawmaker Jake Berry wrote on Twitter in a message he later deleted.

Attempting to reach out to his party, Gove said he was driven by conviction and not ambition, and he had concluded Johnson was not the right man for the top job.

"NO CHARISMA"

"I was so very reluctant because I know my limitations. Whatever charisma is I don't have it," he said. "Whatever glamor may be, I don't think anyone could ever associate me with it."

As one of the leading Leave campaigners, Gove said the next prime minister should be someone who supported exiting the EU, a swipe at May who, like Cameron, was in the Remain camp.

May now says she will implement the voters' will and negotiate to leave: "Brexit means Brexit," she said at the launch of her own bid on Thursday.

A party stalwart whose six years in charge of the law-and-order portfolio is the longest tenure for a century in what is often described as the trickiest cabinet job, May has swiftly emerged as the favorite in a field without Johnson.

Britain's Daily Mail newspaper, a strong voice for Brexit, backed her on Friday as the only one out of five candidates for Conservative Party leader who was up to the job.

The other three are the pensions secretary, a right-wing former defense secretary and a junior minister in the energy department.

Gove said if he were leader, he wanted extensive preliminary talks before Britain invoked article 50, the formal process for leaving the EU, and did not expect this to occur before the end of the year.

He also promised to cut immigration with the introduction of a points system and to end free movement of people from EU countries. European leaders say Britain must retain free movement if it wants access to the EU single market.

Alongside the battle to lead the Conservative Party, the main opposition Labour Party has also turned on itself, with most of its lawmakers in parliament having voted to withdraw support for party leader Jeremy Corbyn, a left-winger.

Party opponents accuse him of leading a half-hearted campaign to stay in the EU, and say he is too weak to win a general election if the new Conservative leader's government falls. He says he draws his mandate from grassroots activists and will not step aside.

The political vacuum in both major parties has added to the chaos at a time when Britain is facing its biggest constitutional change since its empire dissolved in the decades after World War Two.

Labour politicians had been expected to mount a challenge to Corbyn's party leadership this week, but the announcement appears to have been postponed until next week, with some hoping he can be persuaded to step aside.

(Additional reporting by Elizabeth Piper and Guy Faulconbridge; Editing by Peter Graff)