(CNN)As Israeli Prime Minister Benjamin Netanyahu heads to the United States, some former security leaders from Israel have come out against his speech to Congress, set for Tuesday. Speaking at a Tel Aviv press conference, retired Maj. Gen. Amnon Reshef, one of the founders of Commanders for Israel's Security, said the speech -- expected to take a hard line on Iran's nuclear ambitions -- is "a terrible mistake" that will further damage the relationship between the U.S. and Israel. He also said the speech could harm Israel's security by damaging Israel's relationship with other countries. On Friday, Meir Dagan, the former head of Israel's intelligence agency, Mossad, told one of the leading Israeli newspapers, Yedioth Ahronoth: "The person who has caused the greatest strategic damage to Israel on the Iranian issue is the prime minister." Dagan, who was the director of Mossad from 2002 to 2010, continued, "I've seen leaders who made decisions and then later admitted that they had erred. Nobody is immune from mistakes. The difference between him and others is the willingness to take responsibility. He is strong on talk, not in action." Recent polling by CNN affiliate Channel 10 Israel shows Israelis split on the speech, with 38% supporting it and the same percentage opposing it. The remaining 24% are undecided. But another poll from Panels Politics, an Israeli polling institute, indicates 53% of Israelis believe the speech will have no effect on the negotiations between six world powers and Iran over Tehran's nuclear program. Another 30% believe the speech will affect the negotiations. Reshef said this year's elections, which will take place on March 17, exactly two weeks after Netanyahu's speech, are crucial for the peace process. Even after years of failed negotiations, Israel has the opportunity now to restart negotiations with the help of moderate Arab states, he said, while warning that going the wrong direction could push peace further out of reach. Reshef would not specify which political leaders would be the best for negotiations, but he said he trusts Israeli voters to decide for themselves in the upcoming elections. Commanders for Israel's Security is a nonpartisan group of nearly 200 veteran senior security members from the Israel Defense Forces; Shin Bet, Israel's internal security agency; and the police. It is committed to a regional political-security initiative to resolve the Israeli-Palestinian conflict. The group also seeks to normalize relations with moderate Arab states such as Egypt, Saudi Arabia, Jordan and the United Arab Emirates. 6 questions about Netanyahu's visit .
Retired general says Netanyahu speech will damage Israel-U.S. relationship . Poll shows Israelis split on whether they support the speech, with many undecided .