JERUSALEM — In an apparent setback for Prime Minister Benjamin Netanyahu, the longtime Israeli leader on Tuesday fell short of securing a parliamentary majority with his hard-line allies in national elections, initial exit polls showed, putting his political future in question.

Results posted by Israel’s three major TV stations indicated that challenger Benny Gantz’s centrist Blue and White party held a a slight lead over Netanyahu’s Likud party. However, neither party was forecast to control a majority in the 120-seat parliament without the support of Avigdor Lieberman, a Netanyahu rival who heads the midsize Yisrael Beitenu party.

Israeli exit polls are often imprecise and the final results, expected Wednesday, could shift in Netanyahu’s favor. But three stations all forecast similar scenarios.

The apparent deadlock sets the stage for an extended period of uncertainly and complicated political maneuvering, but with Netanyahu in a relatively weaker bargaining position. The parties could be forced into a broad unity government that could push Netanyahu out.