Sanders should make it absolutely clear on where he stands with Obama's FP. He can't just focus on Clinton's record as a Senator while ignoring her as SoS. While his supporters dislike Clinton, they still approve of Obama as a whole so attacking Clinton's tenure would be an indictment of Obama's record as well.
If Sanders focuses on Clinton's Iraq Vote (which SHOULD be a major consideration of any commander-in-chief), Clinton could bring up Sanders' record too. None of these would work in a general election but could bring doubt to his political base (or rather than anti-Clinton base):
-Supported the bombing of Yugoslavia in the 90s, causing one of his aides to resign
-Supported the expensively questionable F-35 project, showing he is not willing to stand up to the military-industrial complex with the same vigour he claims against big banks
-Cosponsored a resolution condemining human rights by Gadaffi, a tatic approval of Obama's Libyan Blitz
-Still a very pretty strong supporter of Israel, like almost every US politician.
He isn't Ron Paul nor Jermey Corbyn, who both have a long voting history of rebelling against party line on foreign policy. There's going to be a GOP Congress blocking his legislation and he should clarify his stances as commander-in-chief, where he does have A LOT of leeway.
People definitely bring up the Libya and Israel thing. Most of Bernie's supporters are too young to remember Yugoslavia, plus even if they could, it's hard for them to be mad about the one time we bombed some White Christians as a favor to Muslims. Anyway, I don't know if it's Hillary's doing, it might just be typical holier than thou leftists. Obviously Clinton can't bring it up directly, since she supported all those things as well. She's even trying to out Israel him now. It would be a good (if dishonorable) strategy to get his voters simply not to turn out though.
