Anti-Brexit demonstrators wave banners and flags outside the Cabinet Office in London, Friday, Aug. 30, 2019. A legal challenge aimed at stopping Boris Johnson's suspension of Parliament has been denied an interim interdict at the Court of Session in Edinburgh on Friday. A cross-party group of MPs and peers filed a petition at Scotland's highest civil court earlier this summer aiming to stop the Prime Minister being able to prorogue Parliament. (AP Photo/Kirsty Wigglesworth)

LONDON (AP) — British Prime Minister Boris Johnson’s decision to suspend Parliament for part of the run-up to the Oct. 31 Brexit deadline faces mounting legal and political challenges ahead of a weekend of planned street protests.

There are three ongoing court tests to Johnson’s plan, which he says is routine but which will shorten the time in which opponents in Parliament could seek to pass legislation blocking a disorderly “no deal” departure from the European Union.

A Scottish judge Friday declined to issue an immediate injunction to block the suspension of Parliament but set up a full hearing Tuesday on the legal bid launched by cross-party legislators determined to keep Parliament in session.

A separate case in London has also received the heavyweight backing of former Prime Minister John Major — a fellow Conservative from Johnson’s party — and from Tom Watson, the deputy leader of the opposition Labour Party.

Major hopes to formally join the case started by activist Gina Miller so he can argue that Johnson has exceeded his authority by asking Queen Elizabeth II to shutter Parliament for several weeks during the crucial period before the Brexit deadline.

“If granted permission to intervene, I intend to seek to assist the court from the perspective of having served in government as a minister and prime minister, and also in Parliament for many years as a member of the House of Commons,” he said.

A case is being heard in Northern Ireland, as well.

The various courts are being asked to intervene in what is seen by Johnson’s opponents as a power grab that undercuts the sovereignty of Parliament.

It is too early to gauge the possible impact of street protests planned for Saturday in London and other major British cities.

Activists hope a massive turnout could influence vacillating members of Parliament when it reconvenes on Tuesday after a summer recess.

Organizers say more than 30 protests have been planned in cities throughout the United Kingdom.