In an interview with Parliament's The House magazine, conducted before the vote, he said they had celebrated after Mrs May was defeated in last month's vote and were not true Conservatives. Lawmakers will vote on each of the selected amendments one by one, before voting to give final approval to the wording of the motion itself.
Britain's opposition Labour party leader Jeremy Corbyn attends a political rally event in Hastings, southeast England on January 17, 2019.
"But isn't it the case you take a no deal off the table that's the surest way of ensuring the other side digs in on their current position".
Defence Minister Tobias Ellwood told BBC Newsnight the ERG was a "party within a party. flexing its muscle" to take advantage of Mrs May's lack of a Commons majority.
Thursday's government motion called for MPs to back its renegotiating strategy, but ERG members believed it also meant endorsing calls to rule out a no-deal Brexit.
May will insist to European Union chiefs that her defeat in parliament on Thursday does not change her belief that her Brexit deal can still achieve a majority - as long as there are changes to the backstop.
The U.K. government is watering down its request for changes to the contentious Irish border "backstop" arrangement as set out in the text of the divorce deal that May struck with the European Union a year ago.
"There doesn't seem to be a majority of MPs asking for anything specific".
If the Government won't change the wording before the vote (at the moment they are sticking with their motion), there could be more heartache over Brexit for the PM.
Valentine's Day was another crunch day for May as MPs gathered to vote on a motion she tabled seeking support for her Brexit strategy.
The British press has surely by now run out of ways to describe the current Brexit-inspired chaos.
In media interviews Grieve said that if May failed to remove the threat of no deal there could be resignations on a scale that might bring down the government.
"She can't keep on just running down the clock and hoping that something will turn up that will save her day and save her face".
George Katrougalos, the Greek foreign minister, said that the vote was "part of the contradictory message that we are receiving as the 27 from the UK".
The resignations are being threatened if it appears likely that Britain faces crashing out of the European Union without a deal, say observers.
The Netherlands is Britain's main trading partner on mainland Europe.
The most closely fought is likely to be Tory Remainer Anna Soubry's, which calls on the government to release the most recent briefing to Cabinet on the implications of a no-deal Brexit.
However, only 24 per cent of Dutch entrepreneurs felt they were well prepared for Brexit, according to a Dutch Chamber of Commerce survey undertaken in December.
But the British premier has hardly any room to maneuver.
"It is too small to appear on the world stage on its own", he added.