Samoa's Supreme Court
Photo: RNZ Pacific / Autagavaia Tipi Autagavaia
The challenge will be heard on Friday with a decision due on Monday.
Also to be decided Monday is FAST's challenge to the extra woman's seat which created the current deadlock.
And six of 28 electoral petitions and counter-petitions have been set down for the weeks commencing 31 May and 7 June.
But if FAST's challenge to the fresh election fails, they will be voided.
The Head of State last week called for a second election as a way to break a month-long deadlock between the caretaker Human Rights Protection Party government and the newcomer FAST party, that has prevented a new government being formed.