Editor's note: Jeremy Ben-Ami is president of J Street, a pro-Israel, pro-peace advocacy organization.
(CNN) -- President Barack Obama's nomination of former Sen. Chuck Hagel to be the next secretary of defense has turned into one of those key moments in U.S. politics that could reverberate for decades. It may determine whether a president still has the right to nominate the Cabinet of his choice or whether political zealots representing a variety of narrow interests get to decide who can and cannot serve.
By all rational criteria, Hagel is supremely qualified to head up the Pentagon. His own service in Vietnam gives him a unique perspective -- he would be the first enlisted man to head the Defense Department.
His two terms in the Senate, during which he was deeply involved in foreign and security policy, have made him familiar with the issues he will need to tackle. He knows many key foreign leaders. And his record of defying his own party to oppose the U.S. military occupation of Iraq means he has the independence and personal courage necessary to advise the president in moments of crisis.
Against this, what do his critics offer?
It comes down to some misspoken words, some taken out of context, from the late 1990s, and his failure to sign a few Senate statements on Iran and Israel -- for each of which he has offered a rational explanation.
Hagel's record of support of Israel is clear and unambiguous and is reflected in his voting record on military aid and in his writings and speeches. But this is evidently not enough to satisfy some critics who equate support of Israel to unquestioning backing for almost every action taken by the Israeli government.
However, what really scares Hagel's neoconservative opponents, who brought us the war in Iraq and would like to sell us a military attack against Iran, is his clear record of favoring diplomatic engagement and other nonviolent means over military action. That doesn't mean Hagel is a pacifist. It means he is a realist who knows the costs of military intervention and needs to be convinced that no other option exists before endorsing the use of force.
Interest groups might legitimately critique any nominee's record in the light of their issues. But senators have a higher responsibility -- not to decide whether they personally agree with every position a nominee has taken but to rule on whether the president's choice is qualified to serve. After all, the president has just won an election and has a mandate from the people to lead.
The Constitution lays it out in simple words: The president "shall nominate, and by and with the advice and consent of the Senate, shall appoint ambassadors, other public ministers and consuls, judges of the Supreme Court and all other officers of the United States..."
The Hagel controversy puts this proposition to the test. If he is rejected, the message to future public servants will be clear -- never rock the boat, always go along with the majority, never stake out an independent position, never take a principled stand and above all, never annoy a powerful enemy.
Some influential lobbies in Congress work mostly through fear. To those who support them without question by signing all their letters and voting on all their legislation, they offer the promise of campaign money and political cover; in other words, a quiet life. But to those who dare to dissent, they offer the threat of political retribution, now and for the rest of a politician's life.
Hagel has dared to annoy a lot of people and that has made him some powerful enemies. But his independence and political courage are the very reasons he should be confirmed, speedily and decisively, by the Senate.
Confirming Hagel will send the message we want politicians to stand up for what they believe. Rejecting him will send the message that to succeed in politics in America today, you have to check your brain and your conscience at the door.
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The opinions in this commentary are solely those of Jeremy Ben-Ami.