Theresa May has seen off an attempt by rebel backbenchers to oust her as Conservative leader and British prime minister.
But she sowed the seeds for her eventual departure by telling Tory MPs that she would not lead the party into the next general election, expected in 2022.
Mrs May won a confidence vote of the 317 Conservative MPs by a margin of 200 to 117 in a secret ballot at Westminster.
But as chaos reigned supreme again in London, calm descended on Leinster House as Fianna Fail agreed to extend the confidence and supply arrangement with the Government.
Micheal Martin said it was in the national interest for his party to provide stability until the outcome of Brexit was clear.
The party leader said his decision was "the right one for Ireland" because "Brexit overshadows everything".
"Fianna Fail is determined that the political chaos we see in London will not be allowed to spread to Ireland," he said.
In a day of high drama, a defiant Mrs May had vowed to fight "with everything I've got" to defend her position, warning that a change in prime minister might have meant Brexit being delayed or halted.
In an early-morning statement, Mrs May said securing a Brexit deal which would deliver on the result of the 2016 referendum was "now within grasp" and said she was "making progress" in securing reassurances from EU leaders on MPs' concerns about the proposed backstop for the Border.
Every MP in her cabinet swiftly issued statements of support and she was greeted by loud cheers from the Tory backbenches when she later faced the House of Commons.
Addressing MPs before the crucial vote, Mrs May said that she accepted she could not fight the next election as their leader.
According to MPs present at the meeting, she also promised to find a "legally binding solution" to ensure that the UK did not get permanently trapped in a backstop arrangement to keep the Irish Border open after Brexit.
The scale of this task was highlighted by Taoiseach Leo Varadkar and European Commission president Jean-Claude Juncker, who insisted in a phone call that the UK's withdrawal agreement "cannot be reopened or contradicted".
DUP leader Arlene Foster, who met Mrs May shortly before the ballot, insisted that "tinkering around the edges" of the agreement would not be enough to win her party's support for the deal.
Mrs Foster, whose 10 MPs prop up the minority Conservative administration, said she told Mrs May that "we were not seeking assurances or promises, we wanted fundamental legal text changes".
Back in Leinster House, the mood was very different as Fianna Fail promised there would be no election in 2019.
Mr Martin said the country needed to focus on Brexit and for that reason, his party would facilitate the minority Government's survival. He talked about the uncertainty, about the problems in housing and health, and about how Fianna Fail had ignored "many provocations" from Fine Gael in recent months.
"There has been no talk from us about oiling printers or careless talk about elections in the middle of sensitive negotiations," he said. "In normal times, there would be no issue. An election now would be the right thing for our country."
In his Dail statement, Mr Martin added: "Free of Brexit uncertainty, there can be an election about the need for a new approach to housing, about ending systematic political failures in health and about addressing the needs of people who want a government which understands their concerns."
The Fianna Fail leader did not make any budget demands of Fine Gael - but the party has a list of legislative priorities it wants expedited.
The Herald has established Mr Martin's list includes tougher laws around parole and bail and regulation of variable mortgage interest rates.
The list also includes a bill by backbench TD James Lawless, which aims to make political advertising online more transparent, and a clampdown on fake social media accounts.
Privately, Fine Gael ministers were jubilant last night - but Tanaiste Simon Coveney, who was involved in the review, said the country was the winner.
He praised Fianna Fail, saying the Irish political system showed it could "respond when the country needs them".