"Clinton aides have said that on a slew of issues, Sanders is not far from the party. But the issue of U.S. policy toward Israel — which a Sanders adviser said “absolutely, legitimately will be a point of
conversation” — has made some of Clinton’s backers nervous.
(...)
Speaking last month during a contentious debate with Clinton, Sanders— who declared himself “100 percent pro-Israel” — said that Israel’s 2014 military assault on the Gaza Strip was “disproportionate” to the threat posed by Hamas rockets launched from the Palestinian territory
into Israel.
(...)
“On one hand there is not an enormous amount of difference between them. They are both pro-Israel, they are both pro-peace,” said one longtime Clinton supporter. “But in the context of the campaign terms like ‘even-handed’ can come to mean that the United States is signaling a shift” — and Clinton would oppose that."