Ireland's minority government was on the brink of collapse Friday after the main opposition party submitted a motion of no-confidence in the deputy prime minister just weeks before a key summit on Brexit.
Irish Prime Minister Leo Varadkar, leader of the Fine Gael party that heads the government, has ruled out the resignation of his deputy Frances Fitzgerald.
But opposition Fianna Fail leader Micheal Martin said there would be an election if she did not step down.
Fianna Fail props up the minority government, and the prospect of a snap election before Christmas looms if it removes its support.
Fitzgerald "should step aside in our view and that would avoid a general election," Martin told RTE public radio.
The motion is set to be voted on next Tuesday, pushing Varadkar's minority government to the brink ahead of a key summit next month with EU leaders where the issue of Ireland's post-Brexit border with Britain will be on the agenda.
Ireland is pushing EU leaders to ensure its concerns about the border with British-ruled Northern Ireland are taken into account before Brexit talks can continue, adding an unexpected hurdle to Britain's plans.
- 'Enormous issue' -
Irish Foreign Minister Simon Coveney arrived for a meeting in Brussels on Friday, accusing Fianna Fail of jeopardising the national interest.
"Fianna Fail are behaving recklessly here," he told reporters.
"We have a precarious situation with the main opposition party that signed up to a agreement in the country's interest... now effectively breaching that and risking an election at a time when there are some really, really serious issues for the government to manage," he added.
Both parties said that a vote, if necessary, should be conducted as soon as possible, with senior government figures suggesting the week of December 18.
The crisis centres around claims that Fitzgerald, who was minister for justice between 2014 and 2016, was aware of attempts to undermine police whistleblower Maurice McCabe, who had alleged corruption and malpractice within the force.
"This is an enormous issue, it's something that is at the core to every citizen of this country," Martin told RTE radio.
Third party Sinn Fein has also tabled a similar no-confidence motion in Fitzgerald, but outgoing party president Gerry Adams has said he will not lead the party into any snap election.
The EU has demanded "sufficient progress" be made on the issue of the border if Brexit talks are to move onto the next phase.
Adams has called upon Varadkar -- as the leader of an EU country -- to veto an agreement between Britain and the bloc if there are no guarantees that the border will remain open.
Arlene Foster, leader of Northern Ireland's Democratic Unionist Party, which props up the Conservative Party in Westminster, on Friday accused the Irish government of using the Brexit negotiations "to put forwards their views on" Irish unification.
"We have heard from the foreign ministry of the Republic or Ireland talking about his inspiration for a united Ireland," she told BBC Radio 4's Today programme.
"He should not be using the negotiations to talk about those issues."