Israeli Prime Minister Benjamin Netanyahu’s challenger for the post of ruling Likud party leader is picking up more endorsements ahead of the official launch of his primary campaign on Monday. Gideon Saar’s associates expect about 1,000 party activists to attend the launch and have been buoyed by support of a half-dozen Likud lawmakers, including the powerful chairman of the party’s executive body. Saar’s leadership bid marks the first serious internal challenge to Netanyahu in his decade-plus in power.