It comes a day after Leo Varadkar's shock announcement that he was standing down as Fine Gael leader and would step aside as taoiseach once his successor is appointed.

Heather Humphreys, the social protection minister, and Jennifer Carroll MacNeill, the minister of state, both ruled themselves out on Thursday afternoon, paving the way for Mr Harris.

Justice minister Helen McEntee ruled herself out as a leadership candidate earlier on Thursday, as Fine Gael politicians began to publicly back Mr Harris, the minister for further and higher education.

One of those was Ms McEntee herself, who described Mr Harris as "a great colleague" and "a great communicator".

"I know he will bring huge energy to this important role," she posted on X.

It is expected Mr Harris will confirm his intention to run for the leadership later on Thursday.

If he were to take over from Mr Varadkar, Mr Harris would become the country's youngest ever taoiseach at the age of 37, taking that title from his predecessor.

Fine Gael minister of state Patrick O'Donovan is also among those who have thrown their support behind Mr Harris.

Read more from Sky News:
Women affected by change in state pension age 'owed compensation'
More than 500 migrants cross English Channel in one day
Emmanuel Macron's boxing photos show off his muscles

He said: "I think at the moment, where Fine Gael is, as we're a year out from a general election, we have plenty of time, and plenty of scope to I think rebuild the organisation, refocus on the issues that are of importance to us and I think Simon is best placed to do that."

Both Fine Gael and their largest coalition partner, Fianna Fail, are trailing the main opposition Sinn Fein party in the polls.

Whoever wins the leadership will have up to 12 months before a general election to try to overturn a wide opinion poll deficit.

Others backing Mr Harris include Fine Gael TD and junior minister Neale Richmond, TD and former junior minister Frank Feighan, senators Tim Lombard and Michael Carrigy and MEPs Frances Fitzgerald and Maria Walsh.

Enterprise minister Simon Coveney, who ran against Mr Varadkar in the last Fine Gael leadership contest, ruled himself out on Wednesday.

Mr Harris was the early favourite with many bookmakers and had the backing of several politicians before nominations opened.

Click to subscribe to the Sky News Daily wherever you get your podcasts

However, any rival candidate still has until Monday to enter the race.

Mr Harris first became a member of parliament at the age of 24, after being elected as a local councillor in his native county of Wicklow, two years before in 2009.

His public profile rose significantly when he served as the country's health minister during the COVID-19 pandemic. Before that he also served as a junior minister in the finance department from 2014 to 2016.