Northern Ireland will score an historic first on Monday when a republican will be elected Speaker at Stormont for the first time.
Until now the post has always been held by unionists or Alliance Party members.
The new Speaker is expected to be Mitchel McLaughlin, a Sinn Fein MLA for South Antrim.
The decision to allow a Speaker to be elected was taken at a meeting of the Assembly's business committee yesterday and the actual election will take place on Monday.
The DUP is not nominating anyone to oppose Mr McLaughlin.
"The election had been on the committee's agenda for seven weeks. Sinn Fein raised it every week, but it was never taken. This week the interim chair was Roy Beggs (UUP), who took it as the first item of business, and Peter Weir (DUP) agreed," said one observer.
Sinn Fein is expected to support a DUP deputy Speaker a week later.
The proposal ends a long-standing impasse between Sinn Fein and the DUP and will be seen by many as a sign that the two parties are learning to work together.
A DUP spokesman said: "In October we said we would honour the commitment first given by the late Ian Paisley to support a Sinn Fein nominee for Speaker for the remainder of this Assembly term when Sinn Fein honoured their agreement to support welfare changes.
"As part of the Stormont House Agreement all five Executive parties including Sinn Fein agreed to implement agreed welfare reform proposals. On that basis we will make good our October commitment and support the election of a new Speaker."
When devolution was set up under the St Andrews Agreement in 2007 the DUP and Sinn Fein agreed to rotate the post of chair.
Mr McLaughlin's predecessor is veteran MLA Foyle MLA Willie Hay who held the post from 2007 until last autumn.
But after Mr Hay resigned resign, the DUP still continued to delay the appointment of a successor.
The DUP said that it would be willing to deal with the issue once the future of the Assembly was secured through a deal on welfare reform, the budget and reform of the institutions at Stormont.
Story so far
Mitchel McLaughlin has been tipped as Speaker at Stormont for several months. Originally from Londonderry, he is now an MLA in South Antrim. He has been a close associate of Martin McGuinness since the late 1970s. He was a major contributor to the Sinn Fein document Towards A Lasting Peace In Ireland, which paved the way to ending violence.