Where a petition claims a seat for a person who has not been
returned as a Member or Senator and a respondent wishes to contend that the
person for whom the seat is claimed was not duly elected for some reason other
than that the person did not have the requisite majority of valid votes, that
respondent shall, within 7 days after filing a notice of appearance, or within
such further time as the Court or a Justice allows, file and serve on the
petitioner a statement of the grounds on which that person intends to rely
setting out those grounds in the same manner in which facts relied on to
invalidate an election or return are to be set out in a petition.