The state senator announced Chicago Alderman Carlos Ramirez-Rosa as his lieutenant governor candidate last week. But in a Wednesday statement Biss says they no longer agree on the "deeply personal" issue.
Biss supports a two-state solution and opposes boycott, divestment and sanctions movement called BDS. It seeks to ostracize Israel over its treatment of Palestinians by lobbying corporations and others to cut ties with the Jewish state.
Biss says he grew up in an Israeli family his great-grandparents didn't survive the Holocaust.
Ramirez-Rosa didn't return a message Wednesday.
Biss say he'll choose another running mate soon. He's among several Democrats vying for the chance to unseat Republican Gov. Bruce Rauner.