Hadash, Ta'al and Ra'am parties, that have announced their reformation during a press conference on Saturday, were joined by the fourth and the most nationalistic Arab party - Balad - to reunite the Joint List. The merger came days before this week's deadline for Israeli political parties to finalize their lineups before the elections.
Israel faces an unprecedented repeat election in September after Prime Minister Benjamin Netanyahu failed to form a majority coalition government. Instead, his ruling Likud party advanced a bill to dissolve parliament, sending Israelis to the polls for a second time in 2019.
Ayman Odeh, head of the Hadash party, said Monday that now that the parties have reunited, they can address the "great challenge" facing the country's Arab minority.
Israeli electoral polls published last week projected that the Joint List could become the third largest party in the Knesset after the September .
The four factions first united in 2015, earning 13 seats in the 120-seat Knesset. But infighting later split the Joint List into two parties, which only won a combined 10 seats amid low Arab turnout in April's election. Around 49% of Arabs cast ballots, down from 64% in the 2015 election.
Last week, former prime minister Ehud Barak and the left-wing Meretz party announced the formation of a merger to form the Democratic Union, whose stated aim is to oust Netanyahu, who became Israel's longest-serving prime minister earlier this month.
Former Justice Minister Ayelet Shaked, who assumed the leadership of her New Right party last week, is negotiating a union with a constellation of religious nationalist parties headed by Education Minister Rafi Peretz. The New Right party failed to win enough votes in April's election to enter the Knesset.