Jerusalem, Aug. 30 -- The leader of the main Arab faction in parliament has shaken up Israel's election campaign by offering to sit in a moderate coalition government.

If that happens, it would upend decades of convention that has relegated Arab parties to the sidelines and could bring down Prime Minister Benjamin Netanyahu.

Ayman Odeh's offer to back Netanyahu's chief opponent, Blue and White chairman Benny Gantz, for prime minister reflects the growing desire of Israel's large Arab minority to take a more active role in shaping the country. It also challenges the longstanding norm that Arabs are out of bounds as political partners with the Jewish majority.

If Odeh can generate enough excitement and boost Arab turnout, it could be eno...