Update: I had a call this afternoon from an AIPACer who took me to task for writing that the 79 Senators who signed the AIPAC-endorsed letter – now over 80 – was "not a slam dunk."

Point taken; getting 4/5 of the Senate to sign anything is no mean achievement.

At first glance, it’s just another of those high-volume, low-meaning Capitol Hill squabbles over letters and non-binding resolutions meant to stake out positions on Israel and the Middle East and give politicians a chance to demonstrate to potential campaign givers their pro-Israel bona fides.

But this time around, with critical congressional midterm elections looming and the J Street lobby and PAC in the mix, the tone of the debate is a little nastier, the pressure on lawmakers greater.

AIPAC, the main force in the pro-Israel lobby, is promoting a letter authored by Rep. Ted Poe (R-Texas) and Rep. Gary Peters (D-Mich.) that supports “Israel’s right to defend itself” and urges members to “remain steadfast in the defense of Israel in the face of the international community’s rush to unfairly judge and condemn Israel in international fora such as the United Nations Security Council.”

I always like letters that use the word “fora.”

J Street, in a letter to lawmakers, is urging them not to sign the AIPAC-endorsed letter without changes.

“The test for Congressional statements should not be their acceptability to any one lobby group (including J Street) but whether they advance the American, Israeli and regional interest in ending the Israeli-Palestinian conflict and achieving a two-state solution before it is too late,” wrote J Street founder and president Jeremy Ben-Ami. “The sign-on letters now circulating in the House and Senate, while expressing strong American support for Israel – a position we endorse – fail to address the impact of the present closure of Gaza on the civilian population, the deep American interest in resolving this conflict diplomatically, or the urgency of moving forward with diplomacy before it is too late.”

A lot of the meaning of the AIPAC-endorsed letter is between the lines. It doesn’t exactly say the Gaza blockade is smart policy, but it says it was "instituted to stop terrorists from smuggling weapons into Gaza to murder innocent civilians."  It doesn’t explain how coriander is turned into bombs.

Both sides are promoting the letters “like billions are at stake,” said a congressional source. Both sides are applying all the pressure they can muster – and a lot of lawmakers aren’t happy with the election-year squeeze on an issue that has little to do with the core concerns of the vast majority of voters, but which is a vital concern to a lot of big-time campaign givers.

It’ s hard to say who’s in the lead right now. The AIPAC-endorsed letters have gathered at least 79 Senate and 279 House signatures (also promoting the letters is Jewish Federations of North America.) That’s not insignificant, but it’s not exactly a slam dunk for the pro-Israel establishment..

A congressional source told me the AIPAC-endorsed letter is “namby pamby”; it may not address humanitarian issues or challenge the blockade, which J Street would like, but it also isn’t exactly a full-throated endorsement of Israel’s policies. So why should lawmakers, especially those facing election challenges this year, go out on a limb for J Street on this one?

With enhanced Iran sanctions on the House to-do -list – and an upcoming resolution on Gilad Shalit – the intense squabble over an essentially meaningless pro-Israel letter “is a little jerky by both sides,” this source said.