If you know the secret to getting Congressional Republicans to cooperate, you should be working in DC and not wasting your talents here. Or if it's Bernie who knows this long sought-after secret, someone should tell him to contact the White House immediately.
But seriously.. I know you likely find my rhetoric disrespectful and glib, but I need to hear more than "it can be overcome" in order to take your position seriously.
Let's say Bernie wins. And the House stays Republican. Meanwhile, the Senate, with its favorable map for the Democrats, gives them a 51-seat majority. Paint us a precise, realistic step-by-step picture of how Congress is overcome.
There's no magic formula to get anyone to agree to anything you want. Like the Iran deal that was brought up earlier: it doesn't have strong majority support of the public, so OF COURSE it won't pressure people into supporting it. Second, the people have to demonstrate their support, not just show it through a poll.
Bernie's agenda, issue by issue, polls with strong majority support, except for a couple things like $15 minimum wage ($10.10 gets majority, $15 doesn't at this time).
So on those issues that DO have strong majority support, public demonstration and pressure can indeed help get things passed.
Again, this is not some "guarantee." It is, however, something that's been done before, when Presidents bother using the bully pulpit to push an agenda that has majority support.
Iran deal does not have majority support. The use of that example earlier in this thread showed a severe lack of analytical thinking.
I also would like to add that even a failed attempt at pushing an agenda can still build momentum to make it happen in the near future afterwards. Progress isn't made when people are holding out for a 100% guaranteed victory. It's made when people are not afraid to fail, to show support and build momentum. If Bernie tries to get college tuition to be free and fails, supporters are not going to say "Well let's never try that again." But what WILL happen is that in the process, arguments are made, information supporting the issue is disseminated to the public, and momentum is built for another run at the issue.
If Clinton tries the same thing, it won't be through public pressure. It will be through attempted backroom dealings. And when those fail, there's no momentum built up in the public sphere. So HOW you fail can make the difference between building momentum for success in a future attempt, or not accomplishing anything at all.
TL;DR you're thinking of working within the sphere of Congress to pass a bill. Same old establishment style of politics. That's why you're not understanding the support for Bernie. Bernie is all about getting the people to rally behind causes that are common sense, and sending the message to ALL politicians that they need to find a way to pass the agenda, or risk being voted out. Using examples of unpopular issues like the Iran Deal is not going to disprove anything.