I'm a NJ Democrat (a state notorious for political corruption), and as, much as I hate to say it not all Democrats are 'saints'. Corruption, along with the lying involved, is not exclusive to Republicans.
That said, currently, during the Trump era, many if not most Republicans are following his lead. Trump is the worst possible example for any Politician, yet many Republicans are taking their cues from him in terms of lying (among other things).
Thing is, there is a balancing act going on. As more and more Republicans begin to act like Trump, lying as often as he does, feeling like they can get always with anything - Democrats are forced to confront their own flirtations with lies and respond aggressively against those who do.
Michele Obama said, famously 'When they go low, we go high'. The thing is, Democrats now, these days, don't have much of a choice in that matter. There is still lying on their part on occasion, but when called out for it, the retribution is swifter and far more cutting. [Consider what happened to Al Franken, for example].
Chaos would ensue if both sides lied with equal disdain for the truth. That is the kind of Chaos that could destroy this country.