Frankly I think Cruz would be easier to beat than Trump. The more people see him the less they like him.

Beloved (if occasionally cantankerous) grandpa vs. that uncle your parents didn't like you being alone with.

Enthusiasm and energy beat smirk and spite any day of the week.

Republican side will be Trump (70%), whoever emerges as the anti-Trump, probably Kasich (10%), or brokered convention, probably Romney (20%). Cruz's chances at the nom are zero. He has nothing to offer outside the Christianist fanatic demographic and is only winning about half of that.

To motivate volunteers and sway change-minded voters in a change election with Bernie as our candidate no matter who they run.

for way too many reasons.

He can easily pull an independent run because contrary to popular belief there are very few sore loser laws for Presidential candidates. His problem will be ballot access since a lot of states close it down in September and August, but that's plenty of time to get signatures.

There's no way they broker the thing and give it to Cruz.

But I don't see him getting the nomination. And I feel that the Republicans have no one that is going to be Bernie. Rubio if they were smart could come close, but he is no where near being able to pull off enough delegates for that. Or Kasich he might do pretty well against Bernie. The problem for Republicans is that their only viable candidates for the nomination are so vile they scare most normal people.