It can be deliberate or — I hate to use the word 'innocent' — unknowing.
If deliberate, it smacks of deceit and ruthlessness.
If the perpetrator is unaware of their hypocrisy, it is symptomatic of a mindset that is incapable of impartiality, an inability to self-examine, a static belief in their, or their party's, absolute rightness.
What brought this to mind recently was the LNP's claims that Bill Shorten is a liar. The Prime Minister repeated this claim so often that it was called the "Kill Bill" strategy.
No recognition is made of the previous prime minister's promises not to implement cost cutting to various services (the ABC, health, education, etc), along with other promises, many of which were broken on his taking office.
Lying has become prevalent in politics recently, and all it achieves is to disillusion and alienate the voting public. There's a price to be paid for that kind of thing and it's not pretty.