After seeing polling trends continue to rise, it seems as though Hillary Clinton has become more aggressive in "attacking" Bernie Sanders throughout the last couple weeks. Don't say this too loud, but a note to the Clinton camp if they intend to get more aggressive: going negative on Bernie Sanders has never worked and has always backfired on his opponents.

After reading a few biographies, Outsider in the White House and Why Bernie Sanders Matters, which tell the history of Bernie Sanders and his previous elections, I've deduced this firm conclusion.

Bernie Sanders is seen as an anti-politician because he has a long history of being an Independent, doesn't look or act like a politician, and spouts ideas that don't instantly appear as "mainstream." However, if you look at Sanders's history, you will see he has already participated in 20 elections throughout his life. You read that right. Twenty elections. Now, he did not win all of these (14/20), but batting .700 is pretty good.

After reading about the outcomes of these 20 elections, it was clear that whenever a Sanders's opponent would go negative against him, it would backfire and Sanders would end up winning the election.

A few excerpts from the books when Sanders won after negative attacks:

1983 Mayoral Election -- "The negative ads boosted Sanders' fortunes..."

1990 State Representative Election -- "As he (opponent) continued to slide in the polls, he (opponent) resorted to a tactic that always helped Sanders: he went negative."

2006 Senate Election -- "Both filled the airwaves with political ads, but Tarrant (opponent) made the mistake of going negative."

The problem with going negative on Sanders is that he's an honest, respectable, authentic and good guy. As most people recognize this, even if they don't agree with his stances, it plays a part in why attacks work to Sanders' advantage. Usually, attacks in politics work because the receiving side has to defend themselves and their positions. But with Sanders, he plays fairly nice and doesn't attack or run negative campaigns. This results in the public seeing Sanders "take the high road" (ie: 'her damn emails'), while the other side is being negative. This just comes off as wrong to people. This effect could be why many people took Lance Armstrong's side when it came to steroids. This could also be why many people backed Joe Paterno throughout the Penn State investigations. This could also be why some people were wary of calling Bill Cosby a rapist. Now don't get me wrong, all of those people allegedly did incredibly appalling things, but it helps illustrate my point. So far, the Clinton camp hasn't done anything terribly negative, but if they do, keep in mind that history repeats itself.

This post originally appeared on Medium.