Rishi Sunak was seen apparently swerving Matt Hancock while greeting Tory supporters following his appointment as Prime Minister.
Footage filmed outside the Conservative HQ today shows the soon-to-be PM shaking hands with Tory MPs and party members, but not Mr Hancock.
A clip shared widely on social media shows Mr Hancock clapping his hands, but Mr Sunak appears to ignore him, as he walks past him and continues greeting other people.
The former Health Secretary had publicly endorsed Mr Sunak, praising his "good character" and "fine judgement".
This morning, Mr Hancock tweeted: "On my way to London to support @RishiSunak . He’s the person our country needs right now as Prime Minister to tackle the huge economic challenges, unite party and country, and build a brighter future for everyone."
He later added: "Huge congratulations to @RishiSunak. He is exactly the Prime Minister we need. All of those who know Rishi well know he has the integrity, ability and experience to lead our country in these troubled times."
The new PM and former Health Secretary worked together in Boris Johnson's Cabinet, but Mr Hancock resigned after it emerged that he had broken his own social distancing restrictions as he was caught on camera kissing and hugging adviser Gina Coladangelo.
Mr Sunak was named the new leader of the Conservative Party today after a truncated leadership contest following Liz Truss's resignation.
Ms Truss announced her resignation on Thursday after 44 days in charge, during which time markets descended into chaos and Tory popularity plunge even further.
Mr Sunak, who served in Johnson's Cabinet as Chancellor during the Covid-19 pandemic, won the race when rival Penny Mordaunt failed to win the backing of enough MPs and after Boris Johnson ditched his own comeback attempt.
He will officially become Britain's next PM tomorrow, Downing Street said.
Following the news, Chancellor Jeremy Hunt congratulated Rishi Sunak on winning the Tory leadership race and said he "can be trusted" to be honest about "the huge economic challenges we face".
Mr Hunt, who backed Mr Sunak in the race, tweeted: "Congratulations to Rishi Sunak, our next prime minister.
"This is a time for honesty about the huge economic challenges we face, and courage in addressing them.
"We have a PM who can be trusted to do just that - and give us all confidence in the huge potential of our country."