To do this Harris needs to take away voters from Trump

You’ve provided no evidence at all for this, and all the available evidence demonstrates the contrary.

Just declaring things to be the case isn’t an argument. You have to bring evidence to bear.

Harris coming out against Israel will give voters to Trump, not take them away from Trump

Again. No evidence, and all the available evidence is to the contrary.

Harris must not come out against Israel before elected or she won’t get elected

Again, all the evidence given shows the opposite.

The vast majority of Democrat voters and a smaller group of Republican voters want to stop arms sale to Israel.

A huge proportion of key voters in swing states want to stop arms sales to Israel.

Voters angry at the Democrats for not stopping arms sales to Israel are actively saying they will abstain or vote Trump.

No group, poll, or campaign has come out to claim they’ll vote Trump if the Democrats stop arms sales to Israel.

All this evidence supports the view that stopping arms sales to Israel will gain Democrats a massive number of additional votes, some of which will be from otherwise Trump voters.

You’ve provided no evidence to the contrary.