Although at the helm of a traditionally dovish party, he reportedly has made a string of hawkish comments in private conversations that place him well on the right of the Israeli political spectrum.
Some observers say that Barak's contention that there is no chance for a peace deal with the Palestinians in the foreseeable future stems from a genuine assessment of Palestinian weakness.
Others claim that Barak, who is also defense minister, is deliberately positioning himself right of center because he believes that's the only way he can win the next election for prime minister.
The Labor Party insists that there has been no change in its support of the peace process, and Barak has reassured party stalwarts that he also believes in the need to explore all peace avenues. He even called Condoleezza Rice on Sunday to reassure the U.S. secretary of state that neither his nor Labor's position had changed on the need to move forward.
Politicians and pundits, however, insist that Barak, who as prime minister in 2000 withdrew unilaterally from Lebanon and offered then-Palestinian leader Yasser Arafat 92 percent of the West Bank, has indeed moved significantly to the right. Some say his reluctance to help advance current peace efforts could ultimately undermine them.
The public furor in Israel over Barak's alleged move to the right follows a recent controversial article in the mass circulation daily Yediot Achronot. With Barak persistently refusing to give interviews, reporter Shimon Schiffer compiled a number of hawkish comments allegedly made by Barak in private conversations. Many were reported as direct quotes.
In the article, Barak reportedly says there is no chance of an agreement with the current Palestinian leadership because Palestinian Authority President Mahmoud Abbas and Prime Minister Salam Fayyad are too weak to deliver. He describes Israeli Prime Minister Ehud Olmert's attempts to launch a new peace process variously as "air," "atmosphere" and "souffle."
Barak also is reported saying that because Abbas and Fayyad cannot be relied on to keep a lid on terror, Israel cannot even think of leaving the West Bank until it develops a system to intercept short-range Palestinian Qassam rockets. Otherwise vital installations, like Ben Gurion International Airport, could become targets.
"Israelis have very sound instincts," Barak said. "You can't feed them fantasies about an early peace deal with the Palestinians. This is not Western Europe or North America."
"We won't be able to consider separation from the Palestinians until we find a way to protect Israeli citizens against all the flying objects whizzing over their heads, from the Qassam to the Shihab," he is quoted as saying, the latter reference to the long-range Iranian missile.
Barak adds that developing the military technology to counter the Qassams could take three to five years. In other words, in his view, no Israeli pullback from the West Bank can take place for at least three years.
Barak is skeptical, too, about the attempt to negotiate a framework agreement with Abbas and Fayyad on the core issues of the conflict -- borders, Jerusalem and refugees -- because he does not believe they can deliver.
He predicts that Olmert, who has taken steps to bolster the Abbas government in the West Bank in the wake of Hamas' takeover of the Gaza Strip, will emerge politically battered from the failed exercise.
"When it all collapses, he will seem divorced from reality," Barak is quoted as saying.
Schiffer claims that Barak is reluctant to take risks for peace that could backfire. For example, Schiffer says Barak has made clear he has no intention of removing roadblocks in the West Bank, despite Olmert's commitment to do so.
Olmert promised Abbas that he would start removing roadblocks well over a month ago, but the defense establishment has yet to present a plan to accomplish the goal.
According to Schiffer, Barak argues that removing roadblocks would probably lead to a terror attack in Israel that would spell the end to all goodwill gestures, including removal of roadblocks. So Barak sees little point in even starting.
Barak reportedly made this argument to Fayyad, Rice and Quartet special envoy Tony Blair, adding that his chief responsibility was to protect Israeli lives.
One explanation for Barak's tough talk is that he is playing politics. Barak figures he will face off in the next election for prime minister against Likud Party leader Benjamin Netanyahu, and to win he will need votes from the center right.
Recent polls show Netanyahu in the lead and Barak a close second. Olmert, who heads the Kadima Party and has dropped steadily in opinion polls since last summer's war in Lebanon, is seen as well behind.
Some pundits warn, however, that Barak could be making a big mistake. They say he should consolidate his own disenchanted center-left camp before looking to the right.
Barak and his inner circle claim the quotes in the Schiffer article are out of context and do not truly reflect Barak's thinking. They say Barak believes every effort must be made to reach agreement with the current Palestinian leadership and he will try his best to facilitate an accord.
Some critics maintain that the ambivalence in Barak's position could in itself hurt the process. In a scathing article in the Ha'aretz daily titled "Barak and the 19 Dwarfs" -- a reference to Labor's 19 Knesset members -- commentator Akiva Eldar slammed the party for not calling its leader to order and demanding a much clearer commitment to peace.
"When the second-most-important political party in Israel, the one that adopted partition as a solution, allows its leader to reject the Palestinian party that accepted this principle, what significance does talk of a diplomatic horizon have?" Eldar asked.
Peacemaking in the current conditions is difficult enough, the liberal camp says. Without Labor's full support, it could prove impossible -- and Barak's lack of faith could become a self-fulfilling prophecy.
Leslie Susser is diplomatic correspondent for the Jerusalem Report