Among those not committed to attend; Vice President Joe Biden. His absence would be viewed as a major slap in the face of the prime minister.
There are several factors in play here. One has to do with Netanyahu. The other with House Speaker John Boehner.
On the one hand, the president doesn’t want to be lectured, directly or indirectly, by Netanyahu, over his negotiations with Iran. Which include no additional sanctions. Netanyahu is very concerned about all this. And will lay out to Congress his reasons why.
The other issue has to do with protocol. Boehner’s failure to notify the White House before announcing Netanyahu’s scheduled address.
Either way, this underscores the rift, not necessarily between the United States and Israel, but certainly between the president and the prime minister.