Commons are considering amendments imposed by the Lords, and the key is the amendment 19, the one that guarantees a meaningful final vote on the Brexit deal to MPs.
His competing amendment could force ministers to hand over control of its Brexit strategy to parliament if there is no deal by mid-February.
Among the 14 amendments to the Bill - set to be voted on by MPs on Tuesday and Wednesday - are changes which would see the United Kingdom stay in the Single Market and would allow Parliament to dictate future negotiating terms.
"I've been through this before when in opposition and now that when we're in Government, because if the House makes the concession of allowing the dialogue to continue and I can see the merit of that happening, it has got to be done in good faith".
Remain-supporting Conservative MPs had threatened to back an amendment to the bill which would have given parliament a more widespread veto.
"The Brexit secretary has set out three tests that any new amendment has to meet - not undermining the negotiations, not changing the constitutional role of parliament and government in negotiating global treaties, and respecting the referendum result".
The Government has won the first votes during today's Brexit showdown.
Until just a few days ago, it looked like members of Parliament would overturn key parts of May's Brexit plans - and in turn wield the power to bring down her government.
In Tuesday's key vote, the government headed off a potential Conservative backbench rebellion and the vote passed by 324 votes to 298.
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He added that the issue requires consultations between the allies. And what "exactly was the president committing to?" he added.
There is a gap between what the Tory Remainer rebels think the prime minister promised them and what the Brexit Secretary David Davis thinks has been promised.
At times ministers engaged in public negotiations from the despatch box, with leading Conservative rebel Dominic Grieve and other rebels later leaving the chamber with the whips to discuss the concessions.
The new amendment will be written up at a later stage with detailed plans and concessions.
He added, however, that if sufficient concessions are not made, there will be another chance for MPs to vote on the matter.
The vote comes after a hard day for the Tories.
In a day of drama, May's position seemed suddenly weaker when junior justice minister Phillip Lee, who has always been critical of the government's Brexit strategy, resigned and said he would vote against the government.
He accused the Government of trying to "limit" Parliament's role and called for another referendum once ministers' chosen path becomes clear.
Opening debate on the flagship EU Withdrawal Bill in the House of Commons, Mr Davis warned that the "cumulative effect" of a series of Lords amendments would "make it impossible to deliver the smooth and orderly exit we want".
Phillip Lee, who resigned this morning, gave an impassioned speech from the "naughty corner" on the backbenches - flanked by Remainers including Bob Neill, Nicky Morgan, receiving congratulations for his decision by Soubry and Sarah Wollaston.