After 10 years of power-sharing at Stormont, Northern Ireland has been without a functioning government since January.
But the latest talks to restore a devolved coalition have broken down.
Here's the crisis explained and a look at what comes next...
What is the latest development?
Northern Ireland Secretary has given Sinn Féin and the Democratic Unionists "a small window of opportunity" to break the deadlock in power-sharing talks to form a new coalition executive in Northern Ireland.
James Brokenshire was forced to intervene after a deadline of 4pm on Monday passed.
He had the power to call an election, reintroduce direct rule from Westminster or delay and play for time. He has picked the third option.
Mr Brokenshire said there was "no appetite for any immediate snap election" from the parties less than a month after the last poll.
But he warned the absence of power was not sustainable and would lead to the Northern Ireland civil service taking control of public service budgets in the short term.
What is the cause of the power crisis?
Mr McGuinness, who died last week, quit in a row over a botched green energy scheme that cost Northern Ireland taxpayers around £500 million.
The disagreement focused on a failure by the former first minister, Democratic Unionist Party leader Arlene Foster, to put in place effective cost controls when she was in control of another department.
Mr McGuinness' resignation triggered an Assembly election in early March.
Why didn't the election solve the crisis?
The election saw the DUP and Sinn Féin returned as the two largest parties.
Sinn Féin significantly increased their vote while the DUP lost 10 seats and the Unionist majority at Stormont. Only one seat now divides them.
Under Northern Ireland's power-sharing arrangement the parties have to form a coalition and fill the roles of first and deputy first minister within three weeks.
The failure to do this and see eye-to-eye in talks has prolonged the crisis.
Is it just the energy scheme that is in dispute?
No. The talks process also has seen the parties divided on a number of issues, including potential funding for Troubles victims and the potential incorporation of the Irish language.
How did the talks formally break down?
The talks effectively ended Sunday when Sinn Féin announced it would not be nominating a deputy first minister in the Assembly on Monday.
The DUP did not attend Sunday's talks because it does not negotiate on Sundays.
Without both first and deputy first ministers, it is impossible to form an executive.
How have the sides explained the failure to solve the crisis?
By blaming each other.
DUP leader Arlene Foster said Sinn Féin's "inflexible" approach to negotiations continued the deadlock, adding: "We are just disappointed that Sinn Féin did not come to the talks in the same spirit as we came to the talks."
Sinn Féin leader Michelle O'Neill rejected the claim, saying: "We came at the negotiations with the right attitude, wanting to make the institutions work, wanting to deliver for all citizens."
What happens now?
The Northern Ireland secretary said he would make a full statement in the House of Commons on Tuesday explaining his plan for a resolution.
Mr Brokenshire warned in a statement that the power crisis was "not sustainable" and would have "consequences" for public services.
"We're rapidly approaching a point at which Northern Ireland will not have an agreed budget," he said.
"From Wednesday financial resources to allow Northern Ireland department to deliver key public services will fall under the control of the Northern Ireland civil service."
The Northern Ireland secretary's announcement to give more time for talks is either calculated to force reconciliation or a last throw of the dice.
His tone was cautiously optimistic but nonetheless devolution in Northern Ireland is hanging by the very finest of threads.