A merger of the Board of Deputies and the Jewish Leadership Council would largely depend on the view of the United Synagogue, US president Stephen Pack said this week.
The Board and the JLC have been in discussions for more than a year over possible unification.
While Mr Pack told a US council meeting on Monday night that he had nothing to report on the progress of the talks, he noted that US congregations made up a majority of the Board.
"It will be our deputies that largely determine what happens," he said. "I think that's a huge responsibility for us."
The council formally approved the admission of Sheffield Synagogue as its first north of England member - and the closure of Barking and Becontree Affiliated Synagogue in east London.
Welcoming Sheffield to the fold, Mr Pack said: "I think it will be the first of many."
The US enjoyed a surplus of £89,000 last year, more than double than budgeted for, its financial director Richard Taylor reported.
Local synagogues paid £150,000 less to the central coffers than they did the previous year.