Write stuff at Yavneh
Yavneh College in Borehamwood is urging parents and other supporters to write to Hertsmere Borough Council backing its planning application for a two-form primary section to open next year.
Governors' chair Sue Nyman said that although much had been done to iron out potential problems, "it is still too early to know whether we will be successful in achieving this deadline".
As well as asking supporters to send letters to the council, Yavneh wants them to sign a petition on the Yavneh College website.
All local synagogues are being encouraged to circulate the message to members.
"We believe there is a real need for a new Jewish school in south Hertfordshire," Mrs Nyman added.
"But we need to convince the council of this."
The primary section would be built on land alongside existing school buildings.
It will comprise 14 classrooms, informal meeting and study areas, a PE hall and other facilities on two floors, plus plentiful outdoor study and play areas.
Yavneh hopes to receive the go-ahead from the council in early autumn.