Warren/Sanders supporters: How do you get your agenda enacted into law?

[Progressive Pessimist]

They won't. Then they will become disappointed, stop voting, and cause a 2010-2016 Republican rebound to happen again and take the country even further back.

Before you accuse me of being biased though (even though Warren is the candidate I am probably the most favorable towards, even if it is a fairly diluted kind of enthusiasm) this will happen with any Democrat who manages to get elected in 2020. It's still better than having Trump for another four years.

Our history is a doomed vicious cycle, and I accept that.

[Progressive Pessimist]

The thing is, Biden's more moderate proposal won't get enacted either.

This right here.

Biden's website actually lists a large number of things he can do with his existing executive authority to improve health care, without having to go to Congress.

https://joebiden.com/healthcare/

For example, here he is wanting to establish a board in HHS to control Medicare prices:

Limiting launch prices for drugs that face no competition and are being abusively priced by manufacturers. Through his work on the Cancer Moonshot, Biden understands that the future of pharmacological interventions is not traditional chemical drugs but specialized biotech drugs that will have little to no competition to keep prices in check. Without competition, we need a new approach for keeping the prices of these drugs down. For these cases where new specialty drugs without competition are being launched, under the Biden Plan the Secretary of Health and Human Services will establish an independent review board to assess their value. The board will recommend a reasonable price, based on the average price in other countries (a process called external reference pricing) or, if the drug is entering the U.S. market first, based on an evaluation by the independent board members. This reasonable price will be the rate Medicare and the public option will pay. In addition, the Biden Plan will allow private plans participating in the individual marketplace to access a similar rate.

That's actually not a bad tactic for him to run with. However, it doesn't mean that he should neglect helping to get as many Democrats as possible elected to the Senate, if he's nominated, so that it can finally be taken back and he can pursue much bolder aspects of his agenda.

There is also the problem of this idea probably not being exciting enough for the base. If he wants to beat Trump, he absolutely has to gin up as much Democratic turnout as possible, and this may not be the policy goal that could do it. That isn't necessarily his fault, but it is the political reality we are living in.