Source: Israel Will Not Challenge Gillibrand

Representative Steve Israel will momentarily announce his decision not to challenge Kirsten Gillibrand for the U.S. Senate seat, said a source close to Israel.

"He is doing it for party unity," said the source.

Israel, in choosing not to run for a seat he terribly coveted, is apparently yielding to the pressure exerted by the Democratic establishment, and especially Chuck Schumer, which made its opposition to a potentially damaging Democratic primary clear in recent days.

Israel, a four-term congressman, had campaigned vigorously for the Senate seat during the appointment process in which Governor David Paterson chose Gillibrand, a first-term upstate representative with a conservative record.  

UPDATE: Here's the statement from Israel's office, saying that President Obama personally called and asked Israel not to run.  

I spoke with President Obama today. He asked me that I not run for the U.S. Senate this year. The President asked me to continue my leadership in Congress, working closely with him to reduce our dependence on foreign oil and create new jobs through an intensified focus on renewable energy and green technology. This is a tough, heartfelt decision for me. I have received encouragement to pursue this fight from all corners of our great state. But in the interest of providing New York and our country with a united front for progressive change, I have decided to continue my efforts in Congress and not pursue a campaign for the U.S. Senate. I want to thank Senator Schumer for his friendship and guidance during this process, and I am especially grateful for the support of my friends and family. I'll never stop fighting for Long Island and all of New York.