MEPs will later debate and vote on the next steps in the Brexit process, as Theresa May continues to try to reach an agreement by Parliament.
A number of amendments aimed at changing the direction of Brexit are taken into account in the debate, which is expected to be a routine procedure.
However, BBC political editor Laura Kuenssberg said the prime minister could once again face defeat.
Some Tory Brexiters refuse to support the government, she said.
# 10 insists that Ms. May is still planning a vote on an agreement, but Labor accuses her of running down the clock to "blackmail" MEPs to support their deal.
The Prime Minister has asked MEPs to approve a motion that merely recognizes the ongoing process and reaffirms its support for the approach.
However, several MEPs have tabled amendments containing alternative plans – including one from Labor, which would force the government to return to parliament by the end of the month to hold a comprehensive House of Commons vote on the Brexit plan.
Another member of the SNP is calling on the government to pass a law that will end the Brexit process.
Commons spokesman John Bercow has yet to decide which ones are actually being considered by the MPs.
However, the influential Brexiters of the Tory-backed European Research Group are upset that they must support the Prime Minister's request.
This is because the view supported by a majority of MEPs last month that the government should seek an alternative to backstop is combined with a separate step to prevent Brexit from taking place without a formal agreement ,
The backstop is designed to prevent the return of customs checkpoints at the Irish border in the event that no trade agreement enters into force.
Group deputy chairman Mark Francois told the BBC: "We can not vote for it because it is currently configured because it does not exclude a deal and cancels our bargaining position in Brussels."
He said members had asked "a request" from Downing Street to change the wording, which, he said, goes back to what the prime minister had previously told MEPs.
"A senior ERG source says it has not decided whether to abstain or vote against, but it will not support the government," said BBC editor-in-chief Laura Kuenssberg.
Most MEPs want to avoid a no-deal scenario, fears of havoc in the ports and business interruption. However, some Brexiteers downplayed this prospect and argue that this is an example of Project Fear.
MEPs rejected the deal with the EU in January with a historic lead and the PM says they are seeking legally binding changes to the controversial "backstop" – the "insurance policy" designed to prevent a return to border control between Northern Ireland and Ireland Irish Republic.
The United Kingdom currently has to leave the EU on 29 March, regardless of whether an agreement has been approved by the subordinates or not.
Could the Brexit cause a Labor split?
By the political editor-in-chief of the BBC, Laura Kuenssberg
You will be used to people in my job saying things like "these are critical days".
And hands up, on many occasions, when a big move is predicted, often a damp explosive comes to quell the expectation.
What I want to say now could be a repetition of this familiar phenomenon. But I'm not the only person in Westminster who wondered this week, after many, many, many months of private talks discussing this possibility, in the next few weeks, maybe even in the next few days, that is something it's actually critical, it's about to start.
What happens next?
The Prime Minister has promised to return to the House of Commons on 26th February with another statement – trigger another debate and vote the following day – if no agreement has been reached by that time.
If an agreement is reached, MEPs will have a second "meaningful vote", more than a month after Mrs May's agreement was rejected in the first.
Ms. May told MEPs on Tuesday that she was discussing a number of options with the EU to ensure legally binding changes to the backstop, including replacement with "alternative arrangements" and a time limit on the duration of the insertion or unilateral exit clause for the UK leave it at a time of his choice.
The EU has further stated that it will not renegotiate the resignation agreement.
European Council President Donald Tusk tweeted on Wednesday that "no news is not always good news". The EU is "still waiting for concrete, realistic proposals from London".
The Prime Minister has also stated that she will lift the condition for a 21-day deadline before a vote on the adoption of an international treaty can take place. This means that they could postpone the final Brexit vote until days before Britain's exit from the EU.
Former Attorney General Dominic Grieve warned on Tuesday that the time has come to ratify a treaty under the Constitutional and Governance Act.
The law requires 21 sitting days before the ratification of an international treaty for MEPs to consider the treaty.
However, Ms May responded: "In this case, MEPs have already debated and approved the agreement as part of the significant vote."
If there were no time for normal procedures, the government would amend the Brexit Act to allow faster ratification.