Professor Alan Dershowitz is a great teacher and role model. No one has defended Israel's cause with greater courage. But I must respectfully challenge his support for Senator Barack Obama on the issue of Israel. In a recent JPost.com blog, Dershowitz wrote: "The election of Barack Obama - a liberal supporter of Israel - will enhance Israel's position among wavering liberals." That is wishful thinking. Dershowitz presumes Obama will support Israel as president. If Obama does not, however, then the political left and the "wavering liberals" will surely follow his lead. And what then? Dershowitz notes that both Obama and Senator John McCain have made strong rhetorical commitments to Israel. However, we must judge the candidates on their actions, not their words. JOHN MCCAIN has been a steadfast friend of Israel for many years. He has visited Israel many times and has constantly supported pro-Israel votes in Congress. He has always backed Israel's right to defend itself. A panel of experts assembled by Ha'aretz concluded that McCain would be the best US president for Israel, regardless of who Israel would choose as its next leader. Barack Obama has impressed pro-Israel voters in recent speeches, but his record is worrying. When running for US Senate, he attacked Israel's security barrier - not just its route, but its existence. He called it a "wall," and told the Chicago Jewish News that it was "yet another example of the neglect of this Administration in brokering peace," though its effect in saving lives was already clear by then. In this campaign, Obama has given voters reason to doubt his commitment to his promises on Israel. Just one day after he told the American Israel Public Affairs Committee that "Jerusalem must remain undivided," he reversed himself, claiming that "the wording was poor." And some of Obama's prominent supporters openly predict he will change course on Israel once he is elected to the Oval Office. We also now know that Obama has associated with the anti-Israel left for years. He participated in Jeremiah Wright's anti-Israel church for two decades. He served on a board that gave tens of thousands of dollars to a group run by former PLO adivser Rashid Khalidi. He employed advisers who backed talks with Hamas and suggested military intervention in Israel. His campaign even met last month with supporters of Hamas and Hizbullah. REGARDLESS, THE question is not, as Dershowitz puts it, whether "both Senator McCain and Senator Obama score very high" on Israel's security. Rather, the question is who scores higher. The answer is clearly McCain. Some Obama supporters counter that Israel needs a US president who will force it to make compromises. But without strong American security backing, Israel cannot take risks for peace. Dershowitz worries about "radical academics" on university campuses "trying to present Israel as the darling of the right and anathema to the left." The answer, he says, is "the election of a liberal president who strongly supports Israel." But surely it is better to defend Israel on the merits than to legitimize a left wing discourse of political correctness that labels and demonizes unpopular views. Appeasement never works. American Jewish leaders forgot that lesson when they bowed to threats from the Democratic National Committee and uninvited Gov. Sarah Palin from the rally against Iranian President Mahmoud Ahmadinejad last month in New York. Obama's left-wing activists will expect payback for their efforts, and now he knows he can take the support of Jewish leaders for granted. I CAN understand the value of showing the world that there are liberal champions who are also strong supporters of Israel. But to treat conservative friends of Israel as it they are an embarrassment - a "shande fur de goyim," as Dershowitz put it in his inspiring book Chutzpah - is to alienate potential allies and to encourage a form of political intolerance that is easily turned against Israel. In his memoir - whose title, The Audacity of Hope, was inspired by Wright - Obama admitted: "I serve as a blank screen on which people of vastly different political stripes project their own views." Supporters of Israel who back Obama are indulging in the same fantasy. We can only hope - at best - that Obama will support Israel in a crisis. But we know McCain will do so, in word and deed. The choice is clear. The writer is is a third-year student at Harvard Law School, and the author of The Kasrils Affair: Jews and Minority Politics in South Africa. He is a McCain campaign volunteer and works for Prof. Alan Dershowitz as a research assistant.

Right of Reply: Compare records, not rhetoric

We hope Obama will support Israel - we know McCain will.