Questions about eligibility under Section 44 have forced the Liberal Party to relinquish three of its preselected candidates in Melbourne just as the election campaign begins.

The party's candidate for the marginal north suburban Labor seat of Wills, Vaishali Ghosh, was forced to step aside over her Indian heritage, while Kate Oski, Liberal candidate for the safe western suburbs Labor seat of Lalor, had to resign because she may be able to claim Polish citizenship through her father.

Helen Jackson, the Liberals' candidate for Cooper (formerly known as Batman), was asked to resign from the contest because she is an Australia Post employee, but she has refused and will soon be disendorsed, Liberal sources say.

Working as a public servant may compromise a candidate's eligibility, according to Section 44 of the Australian Constitution.

The party is scrambling to find new candidates ahead of the close of nominations on April 23, and will need to double-check the eligibility status of their other candidates ahead of the election on May 18.