When Israeli Prime Minister Benjamin Netanyahu said last year that he would address the US Congress to make his case against the Iran nuclear deal, Bernie Sanders was the first US senator to announce that he was boycotting the speech, standing up to the leader of America's closest ally in the Middle East.

As Sanders advances in his bid for the US presidency, becoming the first Jewish American to win a primary in New Hampshire, his foreign policy credentials are suddenly under scrutiny.

Critics say he is not prepared for the international stage, while suggesting that his Middle East policy is anti-Israel.

But to those advocating for a Palestinian state, Sanders' record offers no assurances that he can push back against the influential pro-Israel lobby in the US, and confront Netanyahu, as the presidential campaign moves forward.

WATCH: The US and the pro-Israel lobby

Rami Khouri, a Middle East expert and senior fellow at Harvard's Kennedy School, said "not very much" is known about Sanders' foreign policy, but that the Vermont senator would be "forced in the coming months" to address questions on the Middle East - especially if he continues to gain momentum against Democratic front-runner Hillary Clinton.

"He has not spoken very much about issues in the Middle East," including the issue of Palestinian statehood, Khouri said of Sanders, in an interview with Al Jazeera. "So we can't judge him."

Khouri, however, said that based on Sanders' domestic policies, there are "positive indications" that he would pursue a foreign policy "anchored in justice and fairness".

So far, Sanders' campaign has largely focused on income inequality in the US and other issues on the domestic policy agenda.

But on his campaign website, he also said that to resolve the long-running Israeli-Palestinian conflict, the U.S. must play a "leading role" in creating a two-state solution based on "compromise".

"The Palestinians must unequivocally recognise Israel's right to exist, and hold accountable those who have committed terrorist acts. The Israelis must end the blockade of Gaza, and cease developing settlements on Palestinian land," he said.

As mayor of the city of Burlington, Vermont, Sanders had condemned Israel's treatment of Palestinians in occupied territory in 1988, saying that it was "reprehensible" and an "absolute disgrace".

But as senator he defended Israel's ground invasion of Gaza in 2014.

Al Jazeera has contacted Sanders' spokesman Michael Briggs to discuss the senator's foreign policies but received no response.

Palestinian policies

Whether Sanders can face up to Israel and resolve the conflict with Palestine is another question, experts said.

Hamid Dabashi, a Middle East observer at Columbia University in New York, said that while Sanders may pursue a more "moderate" policy towards the recognition of "Palestinian rights to self-determination", the political leadership in Israel "will demonise" him and block his every move.

"I have no reason to believe that he will have that courage or political will," to take on Israel, Dabashi told Al Jazeera.

"As for [him] being more effective in a resolution of the Palestinian cause, the answer is 'No, he will not'," he said. "The protection of the Israeli settler colony is integral to the U.S. imperial policies in the region."

Still, Dabashi said Sanders' lack of foreign policy experience could be an advantage in dealing with Palestine, as he is not tied up to the "institutional rootedness" of the Oslo Agreement, which he said promotes the "stealing" of more Palestinian land.

Dabashi also said that Sanders would be a better president than Hillary Clinton, saying she has been "deeply embedded" in the "catastrophic U.S. policies" in the Middle East - from the time of the presidency of her husband Bill Clinton to her time as secretary of state.

Domestic president

Max Blumenthal, an author and journalist who has covered Israel and Palestine, said that the self-confessed democratic socialist politician would be more of a domestic president, if elected.

"His agenda is entirely contingent on his ability to break up the big banks, and get radical change in policy on the financial system in the US," he told Al Jazeera, adding that Sanders would see the issue of Israel and Palestine as a "distraction".

Blumenthal said neither Sanders nor his rival Clinton appeared willing "to challenge the power of the pro-Israeli lobby", which he said was dedicated to preserving the "special relationship" between the US and Israel.

"I can imagine that if Sanders, in the unlikely event that [he] gets the nomination, would face enormous pressure from the pro-Israel lobby that would seek to domesticate him," he said.

If Sanders were to resist such pressure, he would fall "under sustained personal attack" and would be called a "self-hating Jew and a Jewish communist", Blumenthal warned.

He added, however, that what is clear in the current campaign is that many of Sanders' supporters are not supportive of Israel.

Meanwhile, Blumenthal said that Sanders' lack of experience on foreign policy "will have no bearing on his performance as president", adding that when Barack Obama was elected in 2008, and Bill Clinton in 1992, they had no experience of foreign policy.

Sanders himself has openly acknowledged that his foreign policy experience is limited compared with Clinton's. But he also said that judgement is important, citing his decision to oppose the invasion of Iraq, which Clinton supported.