Clifford Chance and US firm Rogers & Wells will vote on the firms' proposed merger in June.
A source has told The Lawyer that the firms' executive bodies plan to discuss the issue in May, ready for a partnership vote the following month.
The talks are said to have made excellent progress since last month, when they appeared to have stalled over reconciling the two firms' remuneration structures.
Clifford Chance is firmly wedded to lockstep, while Rogers & Wells' pay structure is merit-based, with a wide disparity between the highest and lowest earning partners.
Clifford Chance is also rumoured to be in merger talks with German firm Boesebeck & Droste and an Australian firm, said to be Mallesons Stephen Jacques.
Clifford Chance is thought to be looking for a three-in-one “big bang” to make it the world's largest law firm.
But the Rogers & Wells talks appear to have moved ahead of other negotiations, especially those in Australia.
It is understood that Clifford Chance is now looking to move forward with its US merger, with the others to follow.
The union with Rogers & Wells would be the first merger between a US and UK firm and it would give Clifford Chance nearly 2,400 lawyers worldwide.
Discussions between the two firms were first revealed in Financial News on 25 January.
Neither Clifford Chance nor Rogers & Wells was prepared to comment on the news as The Lawyer went to press.