KUALA LUMPUR, Malaysia—Malaysia’s former Prime Minister Najib Razak resigned as leader of his political party Saturday and promised to abide by a travel ban, but cracks in the new government began to show as his successor Mahathir Mohamad struggled with factional infighting to assemble a new cabinet.
Mr. Najib and the ruling United Malays National Organization suffered a devastating loss in national elections May 9, paving the way for the first transfer of power in the tropical, resource-rich nation since independence in 1957....