One of the things that happens to candidates who seek high national office like the presidency is that their past comes under the microscope and it often happens that they have said things and supported policies that are at odds with what they say they stand for now and what the voters want. This can lead to them having to give explanations that the impression of the past is misleading or, if that is not plausible, to give apologies and say they have learned from their mistakes.
In the case of Bernie Sanders, however, it is remarkable that he has consistently been on the right side of issues throughout his very long career, with only a very few problematical votes while in Congress. In this link, you can see a clip from 1995 when he was in the House of Representatives when he pounced on a Republican congressman Duke Cunningham (who later went to jail for eight years for bribery) who spoke disparagingly of ‘homos in the military’. Sanders immediately jumped up and castigated him.
As a bonus, in the clip you can see congresswoman Pat Schroeder, who was called a socialist by Cunnigham, who also, more gently, chastised the Republican for his bigoted remarks. Some of you may remember Schroeder. She is an excellent progressive who was first elected to Congress in 1972 at the age of 32 and became the first woman to serve on the House Armed Services Committee. She briefly ran for president in 1987 and retired from Congress in 1996 when she was just 56.
About a decade ago, long after she left Congress, I was waiting for my flight in the boarding area when I saw her also waiting for the same plane. When I see a celebrity, I leave them alone but on this one occasion, I went up to her and told her that in my opinion, she was the best of all the candidates when she ran for president. She seemed genuinely touched and thanked me for taking the trouble to tell her that.