London, UK - Activists in the UK have called on Prime Minister Theresa May to stand down at a large demonstration in London.

Thousands attended Saturday's protest, which was backed by senior members of the opposition Labour Party, as well as grassroots left-wing groups.

The protests come as opponents of the Conservative leader try to up the pressure on her newly formed government, which only received majority backing in parliament after the party formed a pact with the Northern Irish Democratic Unionist Party (DUP).

May failed to secure enough seats to form a Conservative government outright in the June general election and was forced to seek agreement with the DUP to guarantee the ability to pass key legislation.

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John Rees, a writer and activist with the People's Assembly, which part-organised the protest, said he wanted to force the government to call another election.

"No one voted for a government that has to bribe the bigots of the DUP with 1.5 billion pounds ($1.95bn) to cling on to office," he told Al Jazeera, adding "Theresa May is on warning: if she isn't gone by the autumn there will be a protest like no other at the Tory party conference in October."

The DUP deal has been criticised for the large sum of money May released to Northern Ireland to secure it, as well as the DUP's ties to unionist militias and socially conservative platform.

The Conservatives say the deal gives the country the "certainty" and stability it requires over the coming years, as Britain leaves the European Union.

Opponents have also targeted the prime minister over the Grenfell Tower disaster, which killed at least 80 people according to an official estimate that is universally expected to rise.

Critics regard the Conservative party's austerity policies as responsible for the lax safety measures, which led to the deadly fire.

"I feel the Conservatives are responsible for what happened (at Grenfell)," said protester Lottie Bowes, adding: "They (government) have made cuts to social housing and don't care about health and safety rules."

"They've ignored entire sections of the community in this country for too long and now they need to go."

Grenfell inquiry

Conservative figures, for their part, have rejected the accusations and what they term the "politicisation" of the tragedy.

The government has called for an official inquiry into the causes of the fire and has ordered checks on other buildings to ensure they are not at risk.

"I am determined that there will be justice for all the victims of this terrible tragedy and for their families who have suffered so terribly," May said earlier this week.

The main beneficiary of the pressure on May has been the Labour leader, Jeremy Corbyn, who defied expectation during the election to secure more seats for the party.

Opinion polls that once had his party trailing the Conservatives by up to 25 points, now give Labour a lead of around five points.

May has said the current parliament will last for two years to oversee Brexit negotiations, which will conclude with the UK's departure from the EU in March 2019.