Former Conservative Party leadership candidate Matt Hancock has backed Boris Johnson to be the next prime minister, boosting the former mayor of London's campaign.
Despite having ruled out a no-deal Brexit during his campaign, in contrast to Mr Johnson, he said the former foreign secretary was now the best candidate to re-unite the fractured Conservative Party.
Mr Hancock said the Uxbridge MP is "almost certainly going to be our next prime minister", in an exclusive article with The Times.
The endorsement came after the clear frontrunner was criticised for failing to appear in the first of the televised leadership debates staged by Channel 4 on Sunday evening.
The Secretary of State for Health and Social Care dropped out of the race for Number 10 on Friday, after receiving 20 votes in the first ballot of party MPs.
He said he spoke to the remaining six candidates in the race and writes he would "be proud to serve any of them as my prime minister".
But he is backing Mr Johnson, as he believes he is the candidate to bring the country and the party together.
"Having considered all the options, I'm backing Boris Johnson as the best candidate to unite the Conservative party, so we can deliver Brexit and then unite the country behind an open, ambitious, forward-looking agenda, delivered with the energy that gets stuff done...
"Boris is emphatic in public and in private that he wants to be a One Nation prime minister and bring the country together around an optimistic vision for the future," he writes.
"I will hold him to that."
Mr Hancock said the former Foreign Secretary has run a "disciplined campaign" and a "Boris administration will be pro-business, pro-enterprise".
Mr Johnson also picked up the support over the weekend of former work and pensions secretary Esther McVey who was eliminated in the first round of voting by MPs.
His decision to drop out of the race means six candidates remain - Mr Johnson, Jeremy Hunt, Michael Gove, Dominic Raab, Sajid Javid and Rory Stewart.
However, it is far from clear the 20 MPs who supported Mr Hancock in the first ballot will now follow him in backing Mr Johnson, since their stances on Brexit vary greatly.
All candidates - except Mr Johnson - took part in the first televised debate on Sunday night.
Channel 4 staged the debate and left an empty podium for the front runner to represent his no show.
He was taunted about his absence by Foreign Secretary Jeremy Hunt who said it raised questions about his ability to take on the job of prime minister.
"Where is Boris? If his team won't allow him out with five fairly friendly colleagues, how is is he going to deal with 27 European countries?" he said.
But the sharpest exchange came when Dominic Raab refused to rule out suspending Parliament to push through Brexit by the end of October.
"I don't think it is likely but it is not illegal," Mr Raab said.
"The moment that we telegraph to the EU we are not willing to walk away at the end of October we take away our best shot of a deal."
International Development Secretary Rory Stewart said shutting down Parliament was "undemocratic" and "deeply disturbing" and would not work.
Mr Johnson, who has been under fire over his reluctance to face media scrutiny, is likely to face further criticism after refusing to take part in a hustings on Monday organised by political journalists at Westminster.
Instead he chose to use his column in The Daily Telegraph to announce plans to extend full-fibre broadband to every home in the country by within five years, nine years ahead of the Government's 2033 target.
"A fast internet connection is not some metropolitan luxury. It is an indispensable tool of modern life," he said.
"It is therefore a disgrace that this country should suffer from a deep digital divide, so that many rural areas and towns are simply left behind."
Mr Johnson has said he will take part in a BBC debate on Tuesday, after the second round of voting, when the field of candidates will have been whittled down further.