Boris Johnson had to ask the EU for an extension to the UK's 31st October exit date after MPs backed a move to delay approval of the deal on Saturday.
Christian Conservative MP Dame Caroline Spelman told Premier the Prime Minister's deal "isn't perfect" but said: "you probably won't ever get a perfect deal.
But it does remove the backstop. There are aspects of the deal, which could be strengthened during the legislative stage. But in principle, I support the deal."
Ms Spelman says since the European Union agreed a new deal with the Prime Minister and getting the backstop removed, they are two things that "a lot of people didn't think he would actually achieve, but he has managed to do both things.
"I was a remainer, but I have to accept that the referendum went the other way by a small margin. But in our democracy, we respect such small margin. So we need to implement the outcome of the referendum.
"Parliament needs to make sure that we do so safely and in an orderly way."
Foreign Secretary Dominic Raab said he was confident enough MPs would back the deal next week, and Brexit would still happen by the deadline.
No 10 says the PM sent "Parliament's letter" but sees no reason for a delay.
That letter to Brussels came from Mr Johnson but was unsigned, and was accompanied by a second letter - which was signed - saying he believed a delay would be a mistake.
Labour leader Jeremy Corbyn wants his MPs to vote against the deal. Christian Labour MP Stephen Timms told Premier Boris Johnson needs to act responsibly: "I think the Prime Minister should be showing a little bit more maturity, then he seems to be showing with sending off a letter and then another letter, he does hold a great office.
"He should be acting accordingly because even the Prime Minister has to obey the law."
Mr Timms says the vote should go back to the people, he said: "I will be supporting having a referendum on the Prime Minister's deal. I do not think we should just go ahead without checking back to the people who started this off with the referendum three years ago.
"I think we should go back to them and with a complimentary referendum and say, do you want to leave on the basis that the Prime Minister has negotiated?"
The government has vowed to press ahead with the legislation to implement the Brexit deal next week, potentially calling a so-called "meaningful vote" on it as early as Monday.
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