Story highlights All the other candidates are either confirmed speakers or have said they will be accepting their invitation to speak

AIPAC has a tradition of inviting all the presidential candidates in election years to the conference

Washington (CNN) Bernie Sanders isn't attending a major pro-Israel conference in Washington this week.

Sanders, the first Jewish politician to ever win a presidential primary, is the only remaining 2016 contender who will not speak at the American Israel Public Affairs Committee, a major gathering for politicians and Jewish leaders every year.

In a letter to AIPAC President Robert Cohen, Sanders expressed regret that he could not attend the annual conference, but said "issues impacting Israel and the Middle East are of the utmost importance to me, to our country and to the world."

Sanders said he was scheduled to be traveling throughout the West and his campaign schedule prevents him from attending. He said he would send remarks to the organization in the hopes that they could be distributed to members as AIPAC does not permit candidates to address the conference remotely.

Sanders' opponent, Democratic front-runner Hillary Clinton, will be a featured speaker.

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