“Lobbying” is the activity of attempting to influence legislation by privately influencing the legislators. It is the result and creation of a mixed economy—of government by pressure groups. Its methods range from mere social courtesies and cocktail-party or luncheon “friendships” to favors, threats, bribes, blackmail. 
Rand, however, appears go beyond merely equating a mixed economy with government by pressure groups. She seems to have believed that a mixed economy is the cause of warring pressure groups; that, in other words, there would exist no pressure groups, no political faction, no competing political interests under laissez-faire capitalism, so that the problem of faction could be cured merely (per impossible) by instituting laissez faire.
What is wrong with this point of view? The main error is one of mistaking the effect for the cause. Faction (Rand’s “government by pressure groups”) is not the inevitable byproduct of a mixed economy; rather, a “mixed economy” is the inevitable byproduct of faction. As James Madison put it: “Liberty is to faction what air is to fire, an aliment without which it instantly expires.”
Rand’s cure for faction is no cure at all, but on the contrary, is the very cause of faction. Indeed, for Madison, there exists no cure for faction, because faction is “sown in the nature of man.” Madison therefore concludes that, since “the causes of faction cannot be removed, … relief is to be sought in the means of controlling its effects.”
What reasons are there to believe that Madison, rather than Rand, is right on this issue? Well, besides the testimony of history, we have the evidence of the science. As Steven Pinker explains in The Blank Slate:
Liberal and conservative political attitudes are largely, though far from completely, heritable. When identical twins who were separated at birth are tested in adulthood, their political attitudes turn out to be similar, with a correlation coefficient of .62… Liberal and conservative attitudes are heritable not, of course, because attitudes are synthesized directly from DNA but because they come naturally to people with different temperaments… But whatever its immediate source, the heritability of political attitudes can explain some of the sparks that fly when liberals and conservatives meet. When it comes to attitudes that are heritable, people react more quickly and emotionally, are less likely to change their minds, and are more attracted to like-minded people. 
In other words, political divisions are built-in: they part of the hardware of human nature and cannot be abolished by merely changing people's premises. There exists an ingrained psychopathology behind the phenomenon of faction that we will expore in the following "Objectivism & Politics" posts, which will cover the politics of human nature. It is on the issue of human nature that Rand’s politics goes awry. Human beings are not constituted so that they are likely to ever fully accept Rand’s political ideals. This is why her politics, in the final analysis, must be reckoned as “utopian.”