The move came as a senior Conservative source said talks with the DUP on a deal to prop up a minority Tory administration were "progressing well" with "broad agreement" on the principles of the Speech, setting out the Government's legislative programme for the coming year.
Same-sex marriage campaigners in Northern Ireland have urged thousands of people to take to the streets in protest against the DUP's refusal to approve a law change.
Sinn Fein said that it was important there was transparency over any deal between the Conservatives and the DUP, and that compromises over certain policy areas could hinder efforts to form a new Northern Irish executive.
Mrs May needs the support of the DUP's ten MPs to give her a majority in Parliament.
While the DUP continue to hammer out the details of the arrangement with the Tories, the other four main parties at Stormont confirmed they would be meeting Mrs May on Thursday.
The local government has not been in session for months, due to a stand-off between Sinn Fein, the former political wing of the Irish Republican Army, and the DUP, which is supported by former loyalist paramilitaries.
Coli bacteria found in drinking water at US Open
It seems doubtful that Love IV can actually mount a challenge to win this weekend, but he could make the cut and make some noise. Rory McIlroy and Jason Day never recovered from theirs. "I was out of it. trying to stay out of the way of Rory".
An election in March saw the pro-British, Protestant, conservative DUP finish narrowly ahead of Catholic socialists Sinn Fein.
Sinn Fein, SDLP and the cross-community Alliance have all also already made clear that Northern Ireland Secretary James Brokenshire can not chair the ongoing process to restore power-sharing at Stormont due to a perceived conflict of interest caused by the deal.
In a statement to reporters outside afterwards, Mr Adams said: "We told her very directly that she was in breach of the Good Friday Agreement, and we itemised those matters in which she was in default in relation to that agreement".
"In reality, the government is here simply because the DUP allow it to be so", Long said, according to the BBC.
A majority in Northern Ireland wanted the United Kingdom to remain in the European Union, though the DUP backed a divorce from the bloc. Devolved government at Stormont, site of the Northern Ireland assembly, broke down in January and has yet to restart.
London, Belfast, Dublin and Brussels all want to keep the border open, but no agreement has been reached.