The DUP announced in the early hours of Tuesday that the party had endorsed proposals agreed with London on the operation of post-Brexit trade rules that would allow it to end a near two-year boycott of the devolved government.
"That is possible if the (UK) government moves with the speed that I believe they can in terms of what needs to be done (to implement the agreement)," Jeffrey Donaldson told BBC Radio Ulster, when asked if government could be restored within days.
Northern Ireland's main parties will meet later on Tuesday to discuss the restoration of the devolved government, a key part of a 1998 peace agreement that obliges Irish nationalists and pro-British unionist politicians to share power.
Donaldson said the UK government could then publish legislation underpinning the deal as soon as Wednesday.
The legislation will have two elements, he added, one part designed to affirm Northern Ireland's place within the United Kingdom and the other introducing changes to the UK Internal Market Act to "protect the region's ability to trade with the rest of the UK".
However, he also acknowledged that the deal was not perfect.
"Are these proposals perfect? Have we achieved everything that we wanted to achieve? No, we haven't. I will be honest with people about what we've been able to deliver," he said.
(Reporting by Padraic Halpin, editing by Elizabeth Piper)
