Senior DUP figures warned Arlene Foster not to proceed with a controversial bill which led to a rebellion among the party’s assembly team.
Sir Jeffrey Donaldson, Sammy Wilson and Nigel Dodds cautioned her against the Executive Committee Functions Bill.
It followed a warning from a former adviser who said it effectively removed the DUP’s veto over ministers taking decisions the party disagreed with.
The bill passed its final stage on Tuesday but 11 DUP MLAs abstained.
Two more failed to turn up to vote.
It is an unprecedented move and has thrown First Minister Arlene Foster’s authority into the spotlight.
The intervention by the senior DUP figures over the bill was first reported by Radio Ulster’s Stephen Nolan show.
But well-placed sources deny there is any immediate threat to her leadership of the DUP.
DUP MLA Peter Weir said that the party remained united despite the split.
The decision of 11 DUP MLAs to abstain on the Executive Committee Functions Bill, coupled with reports that senior figures in the Westminster group counselled caution, puts a question mark over the authority of Arlene Foster and her current advisers.
It also illustrates the continuing respect commanded within DUP ranks for the analysis of Peter Robinson’s former adviser Richard Bullick.
It seems unlikely, given the pressures of tackling a pandemic, that any of Mrs Foster’s internal critics want to make any more of this in the short term.
However, if a future minister from another party was able to utilise the latest legal changes to push through a policy which is anathema to the DUP grassroots, then those who abstained or argued for delay may raise more questions about their leader’s judgment.
He told BBC News NI: “From time to time there will always be some kinds of disagreements on individual issues but we’ve got to make sure that these things are not blown out of proportion.
“The DUP is united in wanting to deliver for all the people in Northern Ireland and I think people admire the strong leadership Arlene Foster has given, particularly over the last few months with the Covid virus.”
The rebellion came after former DUP adviser Richard Bullick warned that the bill overturned safeguards negotiated in the 2006 St Andrews agreement to stop ministers taking decisions without referral.
He cited the example of Sinn Féin’s Martin McGuinness abolishing the 11-plus exam on his last day in office as education minister in 2002.
During Tuesday’s debate on the bill’s final stage, DUP MLA Christopher Stalford – who voted in favour – said his party fully supported the change, which he said would ensure the continuation of “collective government in the spirit of co-operation”.
But former DUP MLA Jim Wells said many backbenchers were extremely concerned and were only voting for it because they had been whipped by the leadership.
Those who abstained from voting included former ministers Mervyn Storey and Michelle McIlveen.
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The Executive Committee (Functions) Bill, which was fast tracked through the assembly before Stormont went into recess on Tuesday, seeks to strengthen the power of individual ministers and was introduced after a court judgement two years ago over a waste incinerator raised questions about the way executive decisions were made.
Defending the need to fast track the bill, Sinn Féin Junior Minister Declan Kearney said it was to allow decisions to be made on key planning applications.
He said the legislation would provide the clarity needed to increase co-operation within Stormont’s five-party coalition.
The bill was passed by 58 votes to 13 with 11 abstentions and will now go forward for Royal Assent.
The assembly has been adjourned until 7 September.