Benny Gantz, a macho army general who brags about flattening whole residential neighbourhoods with devastating bombings raids, might not immediately come to mind as the darling of Israel’s left wing.

But after years in opposition, some beleaguered leftists say they are taking a chance on him. It is less about who he is, they say, and more about who he is not: Benjamin “Bibi” Netanyahu.

“I’m looking for hope,” said Marsha Weinstein, a clinical social worker who moved from the US to Israel in 1985. “Benjamin Netanyahu is tearing this country apart and it’s heartbreaking … I see creeping fascism.”

Facebook Twitter Pinterest A man walks his dog between election campaign billboards for Benjamin Netanyahu (L) and Benny Gantz in Tel Aviv. Photograph: Abir Sultan/EPA

Israel was founded by socialists but its political left wing is in tatters. Ten years of increasingly rightwing governance under Netanyahu has decimated more progressive factions. “Israel” and “Netanyahu” have become synonyms, say both supporters and critics of the prime minister.

For years, Weinstein voted for Meretz, a social justice party, and then Labour, the political group formed from the social democratic movement that first led Israel. But with neither apparently having a credible chance to take high office, this week she sat at a campaign event for Gantz.

“I know people who served under Gantz, and they say he is an upstanding guy,” she said. “This election is basically a referendum: yes Bibi or no Bibi.”

Gantz, a 59-year-old former head of the Israel Defense Forces, appeared out of nowhere a few months ago. With no political experience, he rapidly rose in the polls and made a deal with the leader of the centrist party Yesh Atid, which has a support base among secular middle-class Israelis. They formed the Blue and White (after the Israeli flag) alliance and now pose the most likely challenge to “King Bibi” in elections on 9 April.

Facebook Twitter Pinterest Supporters of the Blue and White party attend a campaign event for Gantz in Jerusalem. Photograph: Abir Sultan/EPA

Netanyahu, 69, has created coalitions of pro-settlement and ultra-Orthodox factions to survive. Despite facing the threat of indictment in three separate corruption cases, he remains the most likely winner on Tuesday. And to the horror of many Israelis, he is betting on support from far-right Jewish extremists to hold on to power.

Gantz has run a campaign that is light on policies but focuses on how he can “unite” a divided country and reset its democracy. “We need to fix the house,” he said at a rally in Tel Aviv.

He has focused on how members of Netanyahu’s cabinet have battered state institutions. The culture minister, Miri Regev, has tried to cut funding to groups considered not “loyal” to Israel, while the justice minister, Ayelet Shaked, pushed to weaken the Israeli judiciary, which she sees as a barrier to a hard-right agenda.

“The minister of culture is supposed to develop our cultural institutions; she attacks them. The minister of justice is supposed to support our justice system; she attacks it,” said Gantz to applause.

His campaign promises, handed out on blue fliers, read like a series of digs at Netanyahu: “We will fight corruption … we will defend the country’s institutions, including its justice and legal systems.”

Blue and White has said it will impose three-term limits for prime ministers. If Netanyahu wins it will be his fifth.

Michal Cababia, a volunteer in Gantz’s team, said Blue and White was a party that could unify. “Discourse in Israeli society, it’s so divisive. People want change.”

To achieve this, Gantz has attempted political acrobatics: he considers himself leftwing, rightwing and centrist. In the same breath, he will try to woo voters who want to forge peace with Israel’s neighbours and those who see brute force as the only option.

He talks proudly of how his first assignment as a young recruit was to protect the Egyptian president Anwar Sadat during a visit to Israel that later led to a peace deal. And how, two decades later, he was the last soldier to leave Lebanon after its internationally condemned occupation. He jokes how he visits Arab countries “mostly without a passport”, an Israeli phrase for wartime travel.

Facebook Twitter Pinterest Gantz during his time as the head of the IDF. Photograph: Baz Ratner/Reuters

Gantz knows that isolating the right in a country where most people identify with it may not be politically prudent. To court voters who cannot imagine Israel without Bibi, Gantz regularly praises his former boss, saying they are similar. “My name is also Benjamin,” he joked.

He says he is pro-peace, but his policy on the Palestinian people does not appear wildly different to Netanyahu’s. He eschews talk of Palestinian statehood, and argues Israel should maintain control of parts of the West Bank and never give up Jerusalem, including its occupied districts.

One of his major running mates, Moshe Ya’alon, is a hawkish former member of Netanyahu’s Likud party who once trialled segregated buses for Palestinians and Israelis.

Sitting at the back of the room where Gantz was speaking, Weinstein said she was not inspired, but figured he might be “the best of the worst”.

“The bottom line is: does this guy have a chance to beat Bibi?”