The Constitutional Democratic Party of Japan (CDP), the largest opposition party in the Upper House, voted?against a package of bills on the imperial family ¡ª in contrast with the position of the Centrist Reform Alliance (CRA) in the Lower House, clouding the prospect for a merger between the two.

The CDP voted against the bills in an Upper House committee on Thursday. It takes the position that the inclusion of a clause about the male offspring of newly reinstated members of the imperial family becoming heirs to the chrysanthemum throne is akin to a ¡°sneak attack,¡± and that it should be omitted.

A parliamentary panel¡¯s outline of the bills released last month ¡ª which among others, propose reinstating male members of former branches of the imperial family through adoption ¡ª made no mention of the clause in question. But a subsequent government draft of the bills said their future male offspring would become heirs to the throne, which caught some parties off guard.