Marie Rimmer has called plans to ask the Queen to suspend Parliament just weeks before the Brexit deadline an “attack on democracy”.
The Prime Minister confirmed plans to hold a Queen’s Speech on October 14, with the UK set to leave the EU on October 31.
This will mean proroguing Parliament, effectively shutting it down temporarily, just days after MPs return to work in September.
Mr Johnson said his new government will “take the country forward” with a “very exciting agenda”, ahead of the UK’s planned departure from the EU on October 31.
However, the move is being widely viewed as an attempt to thwart remain MPs from drafting new legislation aimed at preventing a no-deal Brexit.
Marie Rimmer, MP for St Helens South and Whiston, said the decision is “completely unacceptable”.
Ms Rimmer said: “A no-deal Brexit is not what was voted for, nor promised to, the British people and will cause unprecedented damage to our economy.
“To put the Queen in the position where she would be forced to make a political choice, demonstrates the lack of respect Boris Johnson has for our institutions, traditions and the British people.
“What we are witnessing here is an outright attack on British democracy and I can assure every single one of your readers that the Labour Party will fight this with every fibre of our being.”
Parliament is normally suspended for a short period every year, carried out by the Queen on the advice of the Prime Minister.
This does not always happen, as was the case in 2018 when Theresa May decided against doing in order to push on with her Brexit plans.
Proroguing Parliament closes the previous session and begins a new one.
No debates or votes are held during this time and most laws that have not completed their passage through Parliament are lost.
The decision to prorogue Parliament now is seen as controversial because it would sideline MPs at a crucial point in the Brexit process.
When Parliament resumes it will have just weeks to finalise the details of its departure from the EU.
The Prime Minister insisted MPs will have “ample time” either side of the EU’s planned Brexit summit on October 17 to debate the UK’s departure.
Mr Johnson has now written to MPs to outline his plan to prorogue Parliament.
The move has been criticised from members of his own party, including House of Commons Speaker John Bercow.
Mr Bercow, who does not traditionally comment on political matters, said plans to prorogue Parliament are a “constitutional outrage”.
He said: “However it is dressed up, it is blindingly obvious that the purpose of prorogation now would be to stop Parliament debating Brexit and performing its duty in shaping a course for the country.
“At this time, one of the most challenging periods in our nation’s history, it is vital that our elected Parliament has its say.
“After all, we live in a parliamentary democracy.
“Shutting down Parliament would be an offence against the democratic process and the rights of Parliamentarians as the people’s elected representatives.
“Surely at this early stage in his premiership, the Prime Minister should be seeking to establish rather than undermine his democratic credentials and indeed his commitment to Parliamentary democracy.”