In Wisconsin, Clinton says Sanders is a Democrat-come-lately Clinton calls herself 'a proud Democrat

[Dragonfli]

47. He has done more work for and caucused with the Dems much longer than she has

She served 8 years in the senate (two of which she spent 98% of her time campaigning and fundraising), that's it, plus four years as an appointed Diplomat where she had a horrid record and had to be replaced by Kerry, because she disagreed with POTUS believing war was the only diplomatic solution for everything.

I can't believe I have to post his Democratic credentials yet again but here you have it

He caucused with the Democrats for, 16 years in the United States House of Representatives, 10 years in the United States Senate;

where he served on many committees Representing the Democratic party such as the:

Committee on the Budget (Ranking Member)
Committee on Environment and Public Works
Subcommittee on Clean Air and Nuclear Safety
Subcommittee on Green Jobs and the New Economy
Subcommittee on Transportation and Infrastructure
Committee on Energy and Natural Resources
Subcommittee on Energy
Subcommittee on National Parks
Subcommittee on Water and Power
Committee on Health, Education, Labor, and Pensions
Subcommittee on Children and Families
Subcommittee on Primary Health and Aging (Ranking Member)
Committee on Veterans' Affairs (chairman)

He has every right to expect respect from those he served with such loyalty and in so many capacities.
The Democratic party must consider him a true blue ally to have given him seats on so many committees.

He was also a founder of the Democratic Progressive caucus.

It appears to me the only one's that are offended by his Independent status are all the Moderate Republicans that are far less honest and register as "Democrats" while voting for Republican policy, those "Democrats" are most often both conservative and liars, among them Hillary Clinton.