The strictly-Orthodox parties Shas and United Torah Judaism are trying to pass legislation that will ensure conversions are only carried out by the state's rabbinical courts.
This follows a ruling by the High Court last Thursday ordering the government to recognise conversions to Judaism carried out by privately-run Charedi batei din.
The Charedi politicians are concerned that the ruling will serve as a precedent for the recognition of conversions by more lenient courts, including a new court formed last year by modern-Orthodox rabbis and those run by the Reform and Conservative movements.
While the state only funds the conversion courts of the Chief Rabbinate, the Law of Return - which bestows the right of Israeli citizenship on Jews and their relatives - has deliberately remained vague over the definition of conversion to avoid a rift with non-Orthodox communities in the diaspora. Due to the Charedi influence on most Israeli coalitions in recent decades, this issue has remained an ongoing battle, with each side trying to push though legislation and launch court battles over that definition.