The UK government says it has received "positive and constructive feedback" from the rest of the EU on its Brexit proposals.
Brexit Secretary Dominic Raab said the Chequers plan had proved "challenging" for some in Brussels - but that European counterparts were "engaging seriously".
The EU's chief negotiator has said he "strongly" opposes parts of the plan.
It has also come under fire from some Tory MPs.
After updating MPs on his latest meeting with the EU's Michel Barnier, Mr Raab was urged by a number of his own Brexiteer colleagues to "chuck Chequers".
Christopher Chope told him that persisting with Theresa May's blueprint for future relations was an act of "self-delusion" given what he said was the EU's unwillingness to accept it.
Meanwhile, campaigners for the public to have the final say on the outcome of the Brexit negotiations have welcomed the GMB union's decision to come out in favour of a new referendum.
The UK will leave the EU on 29 March and negotiations are taking place on the terms of its departure and its future relationship with the remaining members.
In July, the UK government published proposals for how trade with the EU could be managed in years to come.
It includes a "common rulebook" for goods and treating the UK and the EU as a "combined customs territory" in an attempt to minimise red tape for businesses and avoid a hard border in Northern Ireland.
But Brexiteer critics - including former foreign secretary Boris Johnson - say this will leave the UK too closely tied to the EU in years to come, and are campaigning for it to be "ditched".
'Deal or no deal'
Addressing MPs, Mr Raab was urged by one Tory backbencher to "chuck Chequers" in the face of recent criticism from EU negotiator Michel Barnier.
Mr Raab said the European Commission had indeed "raised concerns" but that positive feedback had been received from member states.
Since the government published its proposals in a White Paper, ministers have held more than 60 meetings with EU counterparts, he said.
Mr Raab said the "scope and contours" of the agreement covering the UK's withdrawal were clear.
This would protect citizens' rights and put in place a temporary transition period after the UK leaves, he added.
He also defended the UK's plans for the possibility of no deal being reached, which included publishing 25 notices last month offering advice on how best to prepare for such a scenario, saying: "The UK will be ready for Brexit, deal or no deal."
Labour's Brexit spokesman Sir Keir Starmer said his statement would "reassure nobody", dismissed the Chequers plan as a "fudge" and said there were "huge gaps" in the government's plans for no deal, notably on the Irish border.
Writing in the Daily Telegraph, former Tory leader Lord Hague warned that disunity in the party could trigger a "terrible chain of events over the next seven months".
If there is no agreement that can win the backing of the House of Commons, the UK could face a choice of leaving with no deal or deferring Brexit and holding a new referendum, he said.
"Either of those outcomes could variously involve more serious economic consequences than anything seen so far, the fall of the Conservative government, a general election, and either the election of the dysfunctional Labour Party or another hung Parliament."
Mr Barnier's objections to the plan were underlined during a meeting with the Brexit committee of UK MPs on Monday.
One member of the committee, former Conservative minister John Whittingdale, said it had become clear in the meeting that the EU "just can't accept" the Chequers plan, because it thinks it goes against the principles of the single market.
Mr Whittingdale, who said he was personally "very unhappy" about the PM's plan, said Mr Barnier had instead been open to a free trade deal of "unprecedented closeness".