The release mostly criticized the United States' willingness to accept a Russian compromise to allow Iran develop nuclear energy under Russian supervision.
AIPAC, which clashed with democratic and republican leaders in the past, has until now remained supportive of Bush and his administration, considered to be one of Israel's greatest allies.
However, the pro-Israel lobby set out to target Bush and his strategy, after the president recently reversed his stance on the Iranian issue, and decided to hold off pushing to report Iran's nuclear case to the U.N. Security Council.
'Disturbing shift in Administration's policy'
In a statement to members of Congress, AIPAC said that it "is concerned that the decision not to go to the Security Council, combined with the U.S. decision to support the 'Russian proposal,' indicates a disturbing shift in the Administration's policy on Iran and poses a danger to the U.S. and our allies."
"This decision will facilitate Iran's quest for nuclear weapons and undermines international efforts to stop Iran from achieving such a capability," AIPAC stated in the letter.
Notably, what apparently prompted AIPAC to release the letter were recent statements by Israeli government officials expressing concern over Bush's handling of the Iranian case.