If not, it might spell the end of one of the more colorful careers in Israeli politics.

Mr. Lieberman, 60, was born in Kishinev, now the capital of Moldova, and emigrated to Israel at 20. A onetime nightclub bouncer, he rose through the ranks to be a top leader of the right-wing Likud party and aide to Mr. Netanyahu before quitting, for the first time, in 1997 over a round of concessions to the Palestinians.

He formed Yisrael Beiteinu — “Israel is our home” — as a party for Russian immigrants who favored a hard line in peace talks. He went on to hold, and then noisily quit, jobs as minister of transportation, minister of strategic affairs, deputy prime minister and foreign minister.

A proto-nationalist before it came back into vogue, Mr. Lieberman appealed to his fellow émigrés with heavily accented tough talk: toward Egypt (threatening to bomb the Aswan Dam), the Palestinian Authority (threatening to bomb its offices in the West Bank town of Ramallah), and imprisoned terrorists (to drown them in the Dead Sea). He hinted that he might want to execute Arab lawmakers as “terror collaborators.”

One threat haunted him: Before becoming defense minister, he boasted that if he were given the job, he would give Ismail Haniya, the Hamas leader, 48 hours to return captive Israeli civilians and the remains of two Israel soldiers, “or you are dead.”