A group of up to 60 Tory MPs are said to have initiated action to stop the cut going through. Former chief whip and international development secretary Andrew Mitchell is leading the efforts according to The Telegraph.
Mr Mitchell and Tory rebels are calling on fellow MPs to vote down the cutback.
Mr Mitchell accused Mr Raab of allowing “a dismal start to our G7 premiership”, starting in January.
Speaking to The Guardian he said: “With Joe Biden in the White House, this is a dismal start to the British chairmanship of the G7, and UN climate change conference.
“The 0.7 percent was not just one commitment, it was a commitment to the poor made by every single member of the Commons at the last election, apart from the DUP.
“This is about Britain’s leadership role in the world.”
He warned that family planning would be taken away from 7 million people, “with all the misery that that will entail”.
Mr Mitchell claimed two million children would suffer malnutrition and one million girls “will not be able to go to school”.
He added: “These reductions make little difference to us in the United Kingdom, but they make a massive difference to them.”
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Mr Raab added the Government had “taken legal advice” on the subject.
He noted: “It is very clear that if we cannot see a path back to 0.7 percent in the immediate foreseeable future then the legislation would be required.”
Some were critical of Prime Minister Boris Johnson, accusing him of “going after the money”.
One Government source told The Guardian: “This is the wholesale destruction and dismantling of the British development architecture by Boris Johnson. First he dismantled the Department for International Development, and now he is going after the money.