A majority of Welsh MPs are expected to reject a second attempt by the UK government to block a general election on Monday night.
The UK government is going ahead with the five-week suspension of Parliament later.
Opposition MPs want to see anti-no deal Brexit legislation implemented first.
In the first of a series of votes, 34 Welsh MPs, mostly from Labour and Plaid Cymru, joined others in voting to see government discussions on prorogation.
Six Tories voted with their government against the move, which is intended to force the government to release all documents relating to Operation Yellowhammer, the government’s no-deal contingency plan, shared with ministers since 23 July.
Earlier Plaid Cymru’s Liz Saville Roberts called for the prime minister to be impeached if Mr Johnson ignores the Brexit law, has been given royal assent.
The law mandates the prime minister to request an extension to Brexit from the European Union, aiming to prevent a no-deal scenario on the current exit date of 31 October.
Later members of the opposition, including Labour, Plaid Cymru and Liberal Democrat MPs, are expected to reject calls from the government for an early general election.
Two-thirds of MPs are needed to trigger one, following a government request. MPs rejected Prime Minister Boris Johnson’s first request for an election last week.
Earlier on Monday Wales’ 28 Labour MPs, four Plaid Cymru members, independent MP Guto Bebb and the Welsh Liberal Democrat Jane Dodds voted for the Yellowhammer documents to be released.
During the debate on Operation Yellowhammer Stephen Doughty, Cardiff South and Penarth MP, said the UK government could not be trusted.
“It is about our constituents’ lives and the issues that matter to them, which go well beyond Brexit, and it is about the national security and safety of this country.
“The Yellowhammer documents should be made public so that we all know the true risk to this country of a no-deal Brexit.”
Minister Michael Gove, who is in charge of no-deal preparations, said he had given evidence to the EU select committee on Yellowhammer and he hoped “those assurances were sufficient”.
Earlier Brexiteer MP David TC Davies said opposition MPs against a general election before a Brexit extension feared people would vote for Brexit-supporting parties.