Of course, political debate is getting nastier, probably because it is increasingly identity*-based, rather than policy-based. When politics is identity-based, fact and rigorous debate go out the window when people see the other side as a threat to their being, rather than just someone with a different idea that may be worth consideration.
Race, religion, ethnic or national origin, social class, LGBT-or-not, immigrant-or-not, profession*, etc. Increasingly, political affiliation is seen as an identity attribute, rather than a more changeable and flexible status of agreeing with a given party’s policies for now.
**For example, police officers, lawyers, CEOs, Wall Street financiers, factory workers, etc… Scientists are not immune from such attacks like those from creationists, anti-vaccine activists, etc…