Yavneh College Trust chair Malcolm Gordon is "hugely encouraged" by the 300 turnout at an information meeting on the school's proposed addition of a primary section on its Borehamwood site.
The plan is to apply for a two-form entry free school with a target opening date of September 2016.
"That there is a shortage of primary school places locally is not a matter for dispute," Mr Gordon said, "especially with so many new homes going up in the area and hundreds more about to be built. And Yavneh College itself is once again over-subscribed this year. In view of this, I am cautiously optimistic about the prospects of our application, which we hope to be in a position to submit towards the end of May."
Another group in the area is preparing an application for a pluralist Jewish primary, but Mr Gordon was confident that this would not impact on Yavneh's plans.
To demonstrate support for the project, an online survey had been commissioned for parents of prospective pupils and other interested parties. Mr Gordon said it had elicited a positive response.