Time is running out for "Remain"-supporting politicians to prevent an ultimate no-deal Brexit, a London-based think tank said Monday.

The Institute for Government (IfG) said in a 22-page report that many of the previous avenues to stopping no-deal are no longer available to the House of Commons.

The paper, titled "Voting on Brexit: Parliament's Role before 31 October" said that even if members of parliament (MPs) succeeded in amending or voting down new laws, it would only limit the government's powers, rather than manage to prevent a no-deal.

There are now less than 12 weeks before Britain's planned "deal or no-deal" departure from the European Union (EU) on Oct. 31.

MPs will only return to Parliament after the summer recess on Sept. 3 when there will be less than two months before departure day.

The IfG report said MPs and the government are preparing for a Brexit showdown in September and October.

"With the prime minister defining the Oct. 31 deadline as 'do or die,' and a simple choice between deal or no deal, it looks very difficult for MPs who are opposed to no-deal to force a change of approach," the report said.

The IfG said backbenchers have very few opportunities to legislate to stop a no-deal Brexit, and a vote of no-confidence in Prime Minister Boris Johnson would not necessarily stop no-deal.

"It is unclear what would happen if Johnson refused to follow constitutional convention to resign if an alternative majority was possible. This could risk dragging the Queen into politics," the report warned.

The option of a second referendum can only happen with government support, the IfG explained.

Even if Johnson was able to renegotiate some part of the current Brexit deal with Brussels, there would be very little time to pass the legislation needed to implement it.

While MPs could use opposition day debates in the House of Commons or backbench business motions to express their opposition to a no-deal, these would be non-binding and would lack legal teeth.

The IfG said even if rebels from Johnson's Conservative Party decide to go "nuclear" and support a no-confidence vote in the prime minister, there are risks involved in such an approach.

"Crucially, if MPs try and fail to force the government to abandon its no-deal plans, their fall-back option of voting down the government could come too late to make a difference," the report concluded.

"Unless the UK government requests, and the EU grants, a further extension, the UK automatically leaves on the 31 October," the report added.