Taoiseach Leo Varadkar has warned Minister of State Catherine Byrne that she will be sacked if she does not support Minister for Housing Eoghan Murphy in a Dáil vote on Tuesday.

Speaking in New York where he is attending the United Nations, Mr Varadkar said if Ms Byrne did not vote confidence in the Minister for Housing, she could no longer continue as a Minister herself.

“It’s of course the case that if a Minister can’t express confidence in their own colleagues, that they can’t continue as a Minister,” Mr Varadkar said.

“We’re a Government, we’re collective, we make decisions together, and if a Minister doesn’t have confidence in another Minister and votes that way then obviously they couldn’t continue. But, as I say, she hasn’t had that conversation with me yet.”

Mr Murphy is facing a no confidence motion tabled by Sinn Féin on Tuesday night in the Dáil. However, with Fianna Fáil committed to abstaining on the vote under the confidence and supply agreement, Mr Murphy is likely to win the vote.

Mr Murphy told RTÉ's Morning Ireland this morning that he hoped to meet Ms Byrne before the vote. "I hope that she won't be pulled into this Sinn Féin stunt later this evening," he said.

The reports of Ms Byrne’s potential defection on Monday prompted a flurry of headcounts in Government Buildings.

There is scheduled to be an incorporeal Cabinet meeting on Tuesday morning – with Ministers contacted by telephone to secure their assent for a decision – to approve a counter-motion expressing confidence in the Minister for Housing.

Minister for Housing Eoghan Murphy is facing a no confidence motion tabled by Sinn Féin on Tuesday night in the Dáil. File photograph: Gareth Chaney/Collins

Tuesday’s regular Cabinet meeting has been postponed until Thursday due to Mr Varadkar being in New York.

Housing scheme

Mr Varadkar’s comments follow reports that Ms Byrne was considering voting against her colleague, after differences between the two over a large affordable housing scheme in her constituency. Ms Byrne is a Minister of State at the Department of Health and a TD for Dublin South Central.

Mr Varadkar said he would meet Ms Byrne when he returned from the US on Tuesday. A spokesman for Mr Murphy said he was also likely to meet Ms Byrne.

We’re in a housing crisis, we need to build lots of new houses

Ms Byrne surprised Mr Murphy by publicly opposing a new housing scheme in Inchicore at its launch. His plans for the site would see the construction of about 470 homes, 30 of which would be used for social housing with 60 per cent available on a cost rental basis, for rent to low- and middle-income workers.

Speaking at the event, Mr Murphy said the development would be a “game changer” for the rental market. However, at the event, Ms Byrne said it was “probably one of the worst plans” she had seen for the site. She has since continued to campaign against the proposals.

But yesterday the Taoiseach gave his backing to Mr Murphy, saying it was often the case that Ministers had objections to developments in their own areas, but “it is Government policy to build new houses”.

“We’re in a housing crisis, we need to build lots of new houses. It’s Government policy to have high-density housing nearer to our cities and it’s Government policy to have mixed housing, social housing, affordable housing.”

Ms Byrne was uncontactable last night and did not respond to a message. However in a statement on Twitter last night, Ms Byrne she said she wanted to see St Michael’s Estate developed but did not believe a high-density apartment block was the right choice. It would put huge pressure on an “already fractured community”, she said.