Laurence Tribe, the Constitutional law prof at Harvard, has concerns about Bernie.

[Jarqui]

231. "Not being a member of a party hasn't hindered him from introducing or co-sponsoring bills."

That is not the point you made.
You criticized Sanders for not being a leader and getting more of his own bills passed when as an independent, he found out long before Angus King, what Angus King found out: it won't happen.
Angus King only got two local bills to do with Maine passed since 2013.

Independents can introduce bills until they're blue in the face. In earlier years, Sanders did write more bills. The Democrats will put their own version through and take the credit. It is the Democratic party that is effectively getting the bill passed - not the two left leaning Independents in the Senate.

So Sanders accepted his lot in political life and got a lot of amendments through. More than Angus King or anyone else.

For years, being an Independent gave him the freedom to fight for policies he wanted without compromise at the outset. Not having to march to party positions.

As a presidential candidate sponsoring is tougher to do. I just dealt with a BS squabble in this thread about Sanders voting for the 1994 Crime bill because of the Violence Against Women Act it included and the ten year ban on assault weapons after having complained that the bill was too severe on incarceration and would adversely affect blacks. 73% of the black caucus voted for the bill but folks here are trying to vilify Sanders for his vote - cherry picking the incarceration concern and ignoring the trade off. So if you know Congress as well as you claim to, none of this is news to you. A presidential candidate has to be very selective or they'll cherry pick and attack. From that, a presidential candidate is less likely to sponsor and is going to be more careful with how they vote.

Sanders has already made his mark. A lot of the policy positions he took in 2016 that were described as too extreme back then are now being taken far more seriously because of the public response he got from them. Even if he never wins the 2020 leadership race, he has helped shape Democratic policy by putting progressive policies out there and causing people to sit up and notice some of this stuff was not as far fetched as it might have seemed. Some of it has been embraced by other candidates since.

Sanders got scolded as a extremist yet he reminded me of Robert Kennedy "Some men see things as they are, and ask why. I dream of things that never were, and ask why not."

What Sanders has done with the conversation about progressive policies may well be more than a number Senators will ever do in their political lifetime.