Israel’s ruling Likud party has committed to a peaceful transfer of power after its leader Benjamin Netanyahu’s repeated allegations of electoral fraud prompted the security services to warn of the risk of political violence.

The Israeli prime minister’s 12-year grip on power is expected to end on Sunday. This is when 61 members of the 120-seat parliament, the Knesset, will vote in Naftali Bennett, an ultranationalist at the head of an eight-party coalition agreed last week, and designed to oust the five-time prime minister.

As part of repeated efforts to wreck the coalition, Netanyahu, leader of Likud, has described Bennett’s alliance with parties stretching from the fringe-left to an Islamist Arab party as “the fraud of the century”.

“We are witnesses to the greatest election fraud in the history of the country and in my opinion, the history of democracies,” Netanyahu told a Likud faction meeting this week, his language echoing that of the closest ally he has had in his decades in politics: Donald Trump.

There is no evidence of electoral fraud. The coalition agreement was reached after four elections in two years failed to deliver a clear result. If the new government does not secure enough votes on Sunday, then a new election will be called.

Netanyahu’s allies in the ultraorthodox political parties, which have provided the backbone of his coalitions and now face the same exile from power as Netanyahu, have gone even further in their rhetoric. Yaakov Litzman, a former health minister, demanded Bennett, who is religious, remove his kippah (skullcap) in public, painting him as a traitor to Jews.

At least four members of Bennett’s party, Yamina, now live under police protection, in addition to several members of the coalition, and journalists critical of Netanyahu. Rightwing protesters have camped outside the homes of Yamina lawmakers, who have been forced to change their phones after constant death threats. One lawmaker was followed by a suspicious car for an entire day, the online media outlet Walla News reported.

Israel’s Shin Bet security chief Nadav Argaman warned this week that the constant incitement against lawmakers “may be interpreted by certain groups or individuals as one that allows for violent and illegal activities that may even, God forbid, become lethal”.

But Likud, set to go into opposition for the first time since 2009, rejected comparisons to Trump’s last days in office as US president, saying that the allegations of electoral fraud were not meant to be an indictment of Israel’s vote count. Instead, they were highlighting Bennett’s switch from the rightwing camp to the centre-right government he will be heading.

“Bennett hijacked votes from the right and shifted them to the left in direct contradiction to his pledges,” Likud said in a series of tweets late on Thursday. “If this isn’t fraud, we don’t know what is.”

It added: “There always has been a peaceful transfer of power in Israel and there always will be.”

The party had said on June 7 that Bennett was turning “Israel into a dark dictatorship . . . akin to North Korea or Iran”, by considering term-limit laws that could bar Netanyahu from running again. Local media reported that lawmakers are expected to be lobbied during Sabbath prayers by Likud loyalists. The vote will take place on Sunday at 4pm.