Labour will seek to force Theresa May into a second Commons showdown on her Brexit deal by the end of the month.
Shadow Brexit secretary Sir Keir Starmer said Labour will use a Commons amendment to require the prime minister to hold another "meaningful vote" on her deal by February 26.
The move is in response to fears that Mrs May is engaged in a "cynical" attempt to run down the clock before the March 29 Brexit date in order to leave MPs with a stark choice of accepting her deal or crashing out of the European Union without any agreement.
If no deal on the changes to the Brexit Withdrawal Agreement has been reached with Brussels by Wednesday, as seems overwhelmingly likely, Mrs May will address MPs on progress made, say more time is needed for negotiations, and table a "neutral motion" for debate the following day.
Sir Keir's new deadline is expected to be one of a range of amendments tabled for votes on Valentine's Day.
The PM is promising another "meaningful vote" in the coming weeks but Labour will seek to take the decision out of her hands.
"We have got to put a hard stop into this running down the clock," Sir Keir told the Sunday Times. "And that's what we want to do this week."
He believes the prime minister is "pretending to make progress" but actually intends to return to Parliament after the March 21/22 European Council summit the week before Brexit and offer MPs a "binary choice" - her deal or no deal.
"We can't allow that to happen," Sir Keir said. "There needs to be a day when Parliament says that's it, enough is enough."
In the interview Sir Keir described Mrs May's approach as "reckless" and "blinkered" and blamed her "tunnel vision" for the devastating defeat suffered last month when MPs threw out her Brexit deal by a record 230 votes.
"It's this blinkered approach that's got us to where we are, with her never wanting to see where the real majority is in Parliament," Sir Keir said.
Labour leader Jeremy Corbyn, who has written to the Prime Minister setting out his demands for a Brexit deal he could support, accused Mrs May of an "utterly cynical" approach.
In his letter to Mrs May, the Labour leader set out five demands, including a permanent customs union and close alignment with the single market.
The move led to a backlash from pro-EU Labour MPs, but Sir Keir defended the approach and warned against a split in the party.
"When you go through something like Brexit, it is very important that you keep the opposition strong and united," he said.
"We have to keep it together, because in the end, any chance of effective opposition goes if an opposition party starts to lose members from their team."
Treasury Chief Secretary Liz Truss refused to rule out quitting if Mrs May did accept the demand for a customs union.
She told Sky News' Sophy Ridge On Sunday: "I appreciate Jeremy Corbyn has come to the table but the reality is what he is proposing does not deliver on what we want as a country."
Ms Truss said the UK must have an "independent trade policy" and questioned whether a customs union could command a majority in Parliament.
Asked if she could stay in office if the Government backed a customs union she said: "I absolutely do not think that should be our policy."