Politicians of all stripes lie. Here's Nancy Pelosi's politifact.com She said True or Mostly true things 18% of the time. False or Mostly False 36%. And Pants on Fire 7%. They're all liars. That's how they get votes. The only people politicians tell the truth to are the donors in regards to what they're getting for their money.
I think the point here is that the lies in question are of a different nature than your boiler plate political lie. Here, we're talking about denial of basic facts, facts about positions that the politicians themselves are promoting. For example, "Mr. Rubio, you've proposed giving a larger percentage tax break to rich people than middle class. Why?" "No I didn't." Or, Mr. Trump, you said that Mr. Rubio is Zuckerberg's personl senator. Why?" "No I didn't." But then why even release a white paper with your positions on them? These are verifiable words that exist on policy papers, and can be fact checked in minutes. They're not things like disputed budget projections or attack ads that mischaracterize your opponent's stance. The only reasonable explanation is that the politician doesn't want their positions widely known. Saying all politicians lie is true, but the lie is of a different color when quoting from a white paper becomes a "media attack."