The opening of the United Kingdom's Parliament has been delayed by two days because Prime Minister Theresa May has still not finalized a deal with the Northern Irish Democratic Unionist Party over its support for her government.

May needs the backing of the DUP's 10 MPs if her government is to pass any legislation, and also for it to gain approval of the Queen's Speech, which is the formal presentation of the government's plans made at the state opening of Parliament.

Government sources suggested that the Conservatives do not necessarily need an agreement with the DUP before Wednesday, because the DUP would be unlikely to support the opposition Labour Party and its leader Jeremy Corbyn. Even if the DUP abstains from the vote, May should be able to get the Queen's Speech passed.

The DUP dislikes Jeremy Corbyn because of his support for the Northern Irish Sinn Fein Party, which is the DUP's main rival.

May received members of Northern Ireland's other political parties on Thursday to reassure them that any deal with the DUP would not affect the government's neutrality in Northern Ireland. They did not, however, leave reassured.

Naomi Long of the non-sectarian Alliance Party said May did not reassure her of the government's neutrality in Northern Irish matters. She tweeted that she felt that the DUP had leverage over the government.

SNP leader Nicola Sturgeon also said she was concerned about the prospect of a DUP-Conservatives deal.

"I want to record my deep-seated concern and, I believe, the deep-seated concern of many, not just in Scotland, but across the UK right now, at the prospect of some sort of grubby deal between the Tories and the DUP to allow Theresa May to cling to office," she said.

Meanwhile, the leader of the Liberal Democrats party, Tim Farron, resigned on Thursday, saying he found it difficult to reconcile his Christian faith with being the leader of a political party.