The Democratic Unionist Party has agreed to the principles of “confidence and supply” deal in order to support a Conservative government.
This type of deal is not a full coalition, as seen between the Conservatives and Liberal Democrats in 2010, but an agreement in which a smaller party supports the larger one in votes where it might lose.
The development comes after Gavin Williamson, the chief whip for the Tories, spent Saturday in Belfast in talks with the Northern Irish party.
Theresa May was left eight seats short of an overall majority in the general election this week.
The DUP, an anti-LGBT party, won 10 seats.
Details of the deal will be discussed at a cabinet meeting on Monday, and any agreement put in place will come into force when Parliament returns next week.
A No 10 spokesman said: “We welcome this commitment, which can provide the stability and certainty the whole country requires as we embark on Brexit and beyond.”
The Conservatives have been warned that attempting to form a government with the help of the DUP could be detrimental to LGBT rights.
Ruth Davidson, the Scottish Conservative leader, said that she was more committed to LGBT rights than the party.
She spoke to Prime Minister Theresa May to get “categoric assurance” that LGBT rights will not be affected by a Deal between the DUP and the Conservatives.
Davidson told the BBC: “I was fairly straightforward with her [Theresa May] and I told her that there were a number of things that count to me more than the party.
“One of them is country, one of the others is LGBTI rights. I asked for a categoric assurance that if any deal or scoping deal was done with the DUP there would be absolutely no rescission of LGBTI rights in the rest of the UK, in Great Britain, and that we would use any influence that we had to advance LGBTI rights in Northern Ireland.
“It’s an issue very close to my heart and one that I wanted categoric assurances from the Prime Minister on, and I received [them].”
The DUP has stalled all progress on equal marriage in Northern Ireland, and previously supported the introduction of a ‘conscience clause’ to protect people who discriminate against LGBT people.
Stonewall also urged the Tories to keep their promise to LGBT people and not permit progress to equality to be harmed under the DUP.
Stonewall CEO Ruth Hunt said: “We share the concerns of countless LGBT people, and our friends, of all political persuasions who are deeply anxious about the potential Democratic Unionist Party involvement in the new government.
“The DUP have a poor record on LGBT rights. Although the party leader claims they are not anti-LGBT, the DUP have vetoed same-sex marriage in Northern Ireland five times, despite a majority of public and representatives being in favour.”
Hunt added: “It’s important to remember that our values are defined as much by who we stand with as what we stand for.”
The ultra-conservative party which is headed by Arlene Foster has supported the “conscience clause” which would protect those who discriminate against LGBT people because of religion.
The party has also garnered a reputation for being anti-women as it supports a 155-year-old law which can punish women with life imprisonment for terminating a pregnancy.
May pledged to PinkNews that the Gender Recognition Act would be reformed in the next parliament, saying that “the legal process to change their gender can be distressing, so changes do need to be made.”
It remains to be seen how a partnership with the extremely conservative DUP would affect this promise.