Finance Minister Binyamin Netanyahu has vowed to challenge Prime Minister Ariel Sharon in the next Likud Party primary and return to the premiership, according to a Channel 1 report on Wednesday. This follows his late-Tuesday ultimatum to quit the cabinet if Sharon does not agree to a referendum within two weeks.http://www.jpost.com/servlet/Satellite?pagename=JPost/P/Opinion/SectionIndex&cid=1006953079865