But just two weeks later, Israelis went to the polls and surprisingly shifted the country toward the center of the political spectrum – creating a rare window of opportunity for the modern Orthodox rabbi to capture the title of chief rabbi and fulfill his pledge to revolutionize the contentious role that religion plays in the Jewish state.
Stav, a 53-year-old father of nine, heads a private network of modern Orthodox rabbis that is virtually an alternative organization to Israel's state-sanctioned rabbinical bureaucracy. It seeks to put a friendly face on Jewish traditions for secular Israeli Jews alienated by the ultra-Orthodox functionaries that regulate religious services.
The organization, called Tzohar, has gained popularity among secular Israelis with its program that sends rabbis free of charge to officiate at weddings.
Now Stav is waging a highly visible public campaign to change Israel's Rabbinate from the inside. He is being featured frequently in media interviews, is running a Facebook campaign, and appears in large color newspaper ads placed by a group of secular Israelis.
"It's not about public relations and niceness," Stav said in an interview. "There is a critical problem – it's not cosmetic – in the rabbinic system. It needs dramatic changes."
Stav cautiously acknowledges that the stars now seem to be aligned for his hoped-for coup.
Every 10 years, two rabbis – one representing Ashkenazi, or European-descended Jews, the other of Sephardic, or Middle Eastern lineage – are appointed to co-lead the Chief Rabbinate.
It's the country's supreme body overseeing civil services for Jews from cradle to grave – circumcision, marriage, divorce and burial. The current ultra-Orthodox Sephardic chief rabbi will likely be allowed to stay on, but the current Ashkenazi rabbi, Yona Metzger, is vacating his post in the coming months.
For the last two decades, ultra-Orthodox Jewish political parties have wielded outsized influence in governing coalitions, and in turn held sway over the panel of 150 rabbis and politicians that appoints the new chief rabbis.
That balance of power, however, may soon tip in Rabbi Stav's favor.
Prime Minister Benjamin Netanyahu of the leading Likud party needs partners to help him build a stable governing coalition, and two contenders he is courting – the centrist Yesh Atid and the pro-settler Habayit Hayehudi – have made it clear that they do not want the Chief Rabbinate to be dominated by ultra-Orthodox rabbis.
"We certainly support a more moderate and openly Zionistic Rabbinate," said Dov Lippman, a rabbi on the Yesh Atid list.
"One of our main goals is for a Zionist, national religious rabbi to be elected to be chief rabbi," Ayelet Shaked, a Habayit Hayehudi lawmaker, told Israel Radio.
Making Rabbinate more welcoming to seculars
The two parties have not publically endorsed a particular candidate, but a leading member of Stav's rabbinic organization is the No. 2 man on Yesh Atid's parliamentary list, and an official in Stav's organization said Yesh Atid and the chairman of the Jewish Home party are pushing for Stav's candidacy.
The official spoke on condition of anonymity because he was citing private discussions.
The Yisrael Beitenu lawmakers, whose party ran with the Likud on a joint list, also support Stav, said Yekutiel Zafari, a party official.
The decision largely rests on what kind of behind-the-scenes agreements are made with coalition partners.
The rise of Yesh Atid and the Jewish Home reflect something of a backlash against Israel's ultra-Orthodox community, which makes up nearly 10% of the country's population of eight million.
Both parties have pledged to abolish a controversial system that allows ultra-Orthodox males to skip compulsory military service and instead attend religious seminaries.
The ultra-Orthodox have also antagonized the general public in recent years by attempts to impose their social mores, such as separation between men and women, in public spaces like buses and sidewalks.
Unlike many ultra-Orthodox rabbis, Stav served in combat as a soldier and reservist, and his eldest son is a paratrooper commander.
At least three other rabbis are contending for the same position, but Stav is the only one leading a public campaign, promising reform in some of the most controversial ultra-Orthodox practices. He has even published a manifesto outlining what he would change.
He would encourage couples to sign prenuptial agreements to ensure wives can request a divorce, a right not granted to them in the traditional Jewish marriage contract. He would privatize the kosher certification industry and make the chief Rabbinate its regulator, lowering the soaring prices of kosher supervision for the food industry. He would make ritual baths more handicapped accessible, and require ritual circumcisers to refresh their skills in training classes every two years.
What matters most to him is to make the Chief Rabbinate more welcoming to secular Israelis, who make up the majority of Israel's Jewish population.
No to female rabbis, gay partnerships
According to government statistics, more than 9,000 Israeli couples last year sidestepped the Rabbinate and married in civil ceremonies abroad. Civil marriages are virtually banned in Israel.
Stav estimates that a third of all secular Israeli couples choose that option, and says those couples distance themselves from Judaism because they lack the religious marriage documents that would certify their future children as Jewish.
One of his biggest goals is to help Israel's million-plus ex-Soviet immigrants. He vows a massive genealogical research campaign to help immigrants prove their Jewish lineage, and to encourage those who are not of Jewish descent to convert.
"A state in Israel cannot exist when half of the nation thinks the other half is non-Jewish," Stav said.
Though he is seen as a moderate rabbi, he does not support female rabbis or same-sex partnerships, as do rabbis in the more progressive Reform and Conservative movements which are dominant in the US but have a limited presence in Israel.
Orthodox Judaism expert Menachem Friedman says Stav could stir a revolution in the Rabbinate – but the more stringent Orthodox rabbis in the Rabbinate would likely oppose his reforms.
"He is seen as more liberal," said Friedman, a professor emeritus at Bar-Ilan University. "This will put him under pressure and he won't be able to solve all the problems."
And his very public campaign to change the Rabbinate to its core might irk some on the election committee – those who have spent their careers in the very bureaucracy Stav is criticizing.
"Behind the scenes, there was always a political race" for the position of chief rabbi, said Yair Sheleg, a researcher of religious affairs at the Israel Democracy Institute. "But it was always behind the scenes. In public, it's not respectful."