Zac Goldsmith, the Conservative candidate for the London mayoral election, has called Labour "aggressively extreme" with its leader Jeremy Corbyn representing a "real danger" to the Jewish community and the country.
Mr Goldsmith, whose late father Sir James Goldsmith and grandfather were Jewish, will take on Labour candidate Sadiq Khan in May.
The Tory MP for Richmond Park and North Kingston believed that Labour was "in a weird place".
Analysis: What’s really strange is Khan looks a better bet
Speaking to the JC, he said: "It has become so aggressively extreme on so many different levels. To have a Leader of the Opposition, a potential Prime Minister-in-waiting, refer to Hizbollah, Hamas and the IRA as friends, is genuinely worrying.
I’m not taking any votes for granted. I have my work cut out. It will be tough
"It's possible that in four years you could have Jeremy Corbyn as Prime Minister, and five years of government so unfriendly to certain elements of the community, and so hostile to business and with such a skewed view of the big international issues and conundrums we face. I think that's a genuine threat and no one should be complacent."
Mr Goldsmith said Mr Khan was "one of the key architects of what has happened to the Labour Party" having nominated Mr Corbyn to be leader and helped run former leader Ed Miliband's general election campaign last year.
The Tories had become "almost inseparable" from the Jewish community during the same period, Mr Goldsmith claimed.
"I don't think anyone can be in any doubt about the Conservative Party being a friend of Israel. We have seen that through actual interventions - money for the Community Security Trust, a recognition of the threat the community faces - but it goes much deeper than that as well. There's a really solid, positive and good relationship and it will endure."
While relations between Labour and British Jews have deteriorated in the past five years, Mr Goldsmith said he was not complacent about securing support from the community.
"I'm not taking any votes for granted at all. I have my work cut out. It's going to be very tough. I accept I started on the back foot and things have taken longer. But my involvement with the Jewish community has been very solid and hopefully mutually beneficial."
Mr Goldsmith described as "stomach-churning" the incident at King's College London last week in which a lecture was halted after a protest by anti-Israel activists turned violent.
He said: "They crossed the line. Windows were broken. People were made to feel terrified. I've heard people make reference to what happened in Germany 70 years ago with shards of glass shattering and so on."
He added: "People shouldn't feel threatened in London… Broadly speaking it's a model of working diversity, but that requires people of every community to feel safe at all times."
