He says he is determined that the JLM will lead the recovery from the setbacks experienced over the past nine months, since Mr Corbyn's leadership campaign took off.
Mr Newmark is adamant that, to win the battle, Jews have to remain in the party rather than decamp in the face of Jew-hatred. He says: "The rallying call we put out a few weeks ago was that Labour was the party of some of the giants of Jewish involvement in British political life: Lord Barnett, Samuel Silkin, Ian Mikardo, Manny Shinwell and many, many others.
"There is a thirst and an appetite for ensuring that, whatever is going to happen around the party leadership over the next few years, that remains the case."
JLM membership has increased to around 1,000 with a "flood" of affiliate members showing their "support and solidarity".
The group appears to have become a gathering-place for moderates concerned about the direction the party is taking under Mr Corbyn.
JLM was restructured in February, with Mr Newmark, former Jewish Leadership Council chief executive, elected as chairman to take over from veteran MP Louise Ellman.
After a decade in charge, Mrs Ellman has become honorary president.
The new leadership team includes several twenty- and thirty-somethings who have already enjoyed notable achievements in their burgeoning political careers. They are, as Mr Newmark describes them, "bright, young rising stars".
He said: "I want to be the shortest-serving ever chair of JLM. Part of my success will be the fact that, hopefully, one of these people will take over a revitalised organisation in a few years."
Sarah Sackman, the new vice-chair, ran an unsuccessful but impressive campaign in Finchley and Golders Green in last year's general election and will be a shoo-in for another crack at winning a parliamentary seat in 2020.
Former National Union of Students vice-president Rachel Wenstone is JLM's networks officer in the new regime.
Others being groomed for future leadership roles include political education officer Jay Stoll, a senior parliamentary assistant to a Labour MP and former general secretary of the London School of Economics' student union; campaigns officer Adam Langleben, who was elected to Barnet Council two years ago; and youth and student officer Liron Velleman, still a student himself but already holding a role in the party's Chipping Barnet branch.
They provide a clear generational shift and an impressive new face for JLM, which has been on the political scene in this country for 95 years. Its affiliation to Labour as a socialist society means it benefits from inside access to the party's various structures and systems.
JLM's UK branch is a successor to the Poale Zion movement which was founded to promote the Zionist ideal within Labour in the early part of the 20th century.
Since the departures of Tony Blair and Gordon Brown from Downing Street, the party's pro-Israel camp has had a considerably more challenging time.But the scandals of the past year have redefined the scale of the challenge. It is one that many believe is now unachievable, but Mr Newmark thinks otherwise.
"The intention wasn't, and isn't, that the raison d'être of the JLM is to be an organisation fighting antisemitism within the party but, obviously and unfortunately, that has dominated the airwaves for the last couple of months," he says.
"There are some people who have left the party. I respect their position and understand it up to a point but I don't agree with it on any level. If you leave a political vacuum, others will come in and fill it.
"The whole purpose of JLM is to become an organising focus within the party and a space for people who feel Labour is their political home."
The group has started using Labour's Nationbuilder IT system, allowing it to sign up members online for the first time.
The new technology has made it possible to offer student, youth and affiliate memberships, so that supporters, including non-Jews, can back JLM's work without feeling the burden of voting on its internal matters.
Productive meetings have been held with deputy leader Tom Watson and general secretary Iain McNicol. An MP will be appointed as JLM political chair in the coming weeks to strengthen representation in the Commons.
"We haven't yet found a door that's been closed to us," says Mr Newmark. "Everyone is willing to speak to us and engage. We have decent access at every level of the party and certainly a fair hearing wherever we've gone.
"Labour has never been a monolithic party. We still have a tremendous number of friends at every level. That's a position we want to build on."
With the group's centenary due in four years, Mr Newmark is hoping for a bright future.
"There's a huge and proud tradition of Jewish Labour activism in this country. With solid progress and a great team of people over the next couple of years, we hope 2020 will be a celebration of that."
● Gill Kaffash, a former PSC branch secretary this week had her Labour membership appeal rejected. She had questioned the number of Jews who were killed in the Holocaust.
Meanwhile, Bradford's former Lord Mayor quit Labour after an investigation over a series of posts on his Facebook page. Khadim Hussain had been suspended by Labour last month.
Shadow Chancellor John McDonnell, was forced on Wednesday to remove links on his website to a site which had published sympathetic articles about Palestinian suicide bombers.
