Labour will put forward a no-confidence vote in Boris Johnson once it knows it can win, according to Dianne Abbott.
The shadow home secretary said it was above her "pay grade” to confirm whether a vote would take place after Parliament resumes in September confirmed Labour was in talks with the other parties.
“One of the things we have to do is consult with other parties - it's no good moving a vote of no confidence if the Lib Dems, for instance, are not going to vote for it,” she said.
“We are talking to all of the other parties in Parliament and, if we move for a vote of no confidence, we'll want to do it with confidence that we can win it.”
MPs may be unable to stop Mr Johnson pushing through a no-deal Brexit even if he lost a no-confidence vote.
Under the Fixed-Term Parliaments Act, if the government lost such a vote Mr Johnson would have 14 days to win another vote - or for Labour to form its own coalition - before a general election was called.
However, even after that two-week deadline passed, Mr Johnson could still have the power to delay a national vote until after October 31.
Mr Johnson told talkRADIO in June that he wold meet the October 31 Brexit deadline “do or die, come what may”.
Conservative MPs remain divided over the impact of a no-deal Brexit, with Justice Secretary Robert Buckland reiterating it would be “chaos”.