Back in 2009, J Street led a drive for congressional signatures on a letter to President Obama noting Israel’s security interest in controlling the flow of goods in and out of the Gaza Strip, but calling for care to avoid the “de facto collective punishment” of the Palestinians. It garnered 54 signatures.

Despite its earnest qualifications regarding Israel’s security, the letter became a bludgeon for right-wing pro-Israel groups who, in the 2010 midterms, described the “Gaza 54″ as all but appeasers.

Facilitating the polarization was the fact that every single signatory was a Democrat. It’s much easier to muster opposition to an initiative if it can be cast as a partisan issue. It also undercut J Street’s oft-repeated claim that it is nonpartisan.

So when I broke the story last week about the letter to Obama urging him to test Iranian President-elect Hassan Tohan’s bid for dialogue, what struck me was the broader reach of a letter that — like the Gaza 54 letter — bucks the conventions of center-right pro-Israel orthodoxy.

This time, there were 131 signatories, among them 18 Republicans. One of them, Rep. Charlie Dent (R-Pa.), was a lead initiator of the letter. Among groups lobbying for the letter were J Street, Americans for Peace Now and the National Iranian American Council.

The reactions from the same quarters that had slammed the “Gaza 54″ came instantaneously, noting that three quarters of the House of Representatives had failed to sign on. The “appeasement” word cropped up not long after.

Still, the breadth of the signatories and the number of Republicans — 18 is small, but not insignificant — will make it harder to use the letter as a partisan wedge, as will Dent’s seniority. He’s on three appropriations subcommittees, including foreign operations.

I spoke with Dent on Monday and asked him how he approached initiating this letter with Rep. David Price (D-N.C.). His reply had four elements:

– The letter did not obviate demands identified with the pro-Israel center right; it supplemented them, he argued. “The military option remains on the table, and nobody’s talking about loosening sanctions absent major concessions on the nuclear program,” he said.

– From a GOP perspective, the need to exhaust diplomatic options was, if anything, made sharper by Dent’s lack of faith in President Obama’s repeated suggestions that he is willing to use force, if it comes to it, to prevent an Iranian nuclear weapon. “The Obama administration talks about the red lines” with Iran, he said, but its back and forth on red lines with Syria have undercut confidence in its determination to act. “I don’t believe there are people in our country particularly in Israel who believe he will act,” Dent said. “At this point I don’t have confidence the president would exercise that military option. Our best hope to end the program is diplomacy and sanctions.”

– Dent said he had been to too many funerals, had visited with too many amputees at Walter Reed military hospital, not to exhaust all options. “I have been to a number of funerals of constituents who gave what Lincoln called that last full measure of devotion,” he said. “I want to make sure we exhaust all diplomatic initiatives before we get into any military engagement.”

– Dent said he was unstinting in his support for Israel. “I’m a strong supporter of Israel. I believe it’s a strategic asset and ally of the United States. It’s an enduring and ascending relationship. The relationship is institutionally strong and I want to keep it that way.”

But he would not defer to Israeli Prime Minister Benjamin Netanyahu’s assessments. “Prime Minister Netanyahu said Rohani is a wolf in sheep’s clothing, he may be right, but he may not be — we have to test Rohani first.”

Ron Kampeas is JTA’s Washington bureau chief, responsible for coordinating coverage in the U.S. capital and analyzing political developments that affect the Jewish world. He comes to JTA from The Associated Press, where he worked for more than a decade in its bureaus in Jerusalem, New York, London and, most recently, Washington. He has reported from Northern Ireland, Afghanistan, Bosnia and West Africa. While living in Israel, he also worked for the Jerusalem Post and several Jewish organizations.