Secretary of State for Work and Pensions Amber Rudd will back Jeremy Hunt to be the next prime minister.
With nominations in the Tory leadership election opening on Monday, candidates will need eight MPs to back their bid to move forward in the race.
The former Home Secretary has confirmed she will support Foreign Secretary Jeremy Hunt in his campaign to enter Number 10.
In a tweet, Ms Rudd said: "These are serious times and we need a respected statesman who Brussels will listen to, not more bluster.
"Jeremy is a winner with a track record of success in business and in government."
Mr Hunt, 52, already has the backing of Liam Fox, Greg Hands and Mark Field.
He campaigned for Remain in the 2016 referendum and would be a moderate candidate on Brexit in the leadership election.
He has said he would keep a no-deal Brexit on the table, but warned it could be “political suicide” for the Conservatives as Parliament would force a general election.
Ms Rudd has previously warned against leaving without a deal.