The clash in late February on Israel’s popular Channel 2, during the only debate of the election season, was a sideshow to the larger electoral struggle unfolding between Prime Minister Benjamin Netanyahu and his chief challenger, Isaac Herzog. Neither Mr. Netanyahu nor Mr. Herzog appeared at the debate. But it was a breakthrough moment for Mr. Odeh, 40, a little-known lawyer from Haifa who has never served in Parliament yet is suddenly poised to be a power broker in the formation of Israel’s next government.

It was Mr. Lieberman himself who inadvertently helped set in motion a political awakening of Arabs in Israel this election year. Legislation he championed to raise the percentage of votes required to enter Parliament threatened the survival of four small Arab parties, so they decided to unite after years of refusing to do so.

The move has energized many of Israel’s 1.7 million Arab citizens, whose participation rate in elections had been declining as the parties they supported drifted under fractured leadership and hostile right-wing governments.

Now, polls cited by the Israeli media suggest the Arab alliance is likely to become the third-largest faction in Parliament with 13 of its 120 seats, potentially preventing Mr. Netanyahu from cobbling together the 61 seats he needs to form a coalition and stay in power. The same polls show that Mr. Lieberman may have more trouble getting his own Yisrael Beiteinu party across the 3.25 percent threshold he designed.

“The magic turned on the magician,” said Joseph Shakkour, a 25-year-old student and campaign worker for the Joint List, as the Arab alliance is known, using an Arab saying to describe someone getting a taste of his or her own medicine.