JERUSALEM (AP) — An alliance of Arab parties in Israel has finalized its breakup. That sets up the possibility that a small Islamist party could hold the key to Prime Minister Benjamin Netanyahu remaining in office and avoiding prosecution on corruption charges. The Joint List, an alliance of four Arab parties that won a record 15 seats in elections held last year, finalized the split early Thursday. Three will run together and the United Arab List, an Islamist party, will strike out on its own. That party has expressed openness to supporting Netanyahu in return for addressing social and economic issues, and could provide the margin he needs to assemble a ruling coalition.