Lobbying consists primarily speaking about what you think public policy should be. Doing this is explicitly protected as legal by first amendment to the US constitution.

Without the ability for individuals to speak about public policy, how can there be democracy?

There is a problem. Wealthier individuals have the ability to speak more persuasively. They can afford education in rhetoric. They can afford time to learn how laws are written. They can afford time to learn about the particular domain which those laws must govern. They can afford the time to spend honing their arguments. They can afford expensive pieces of equipment like printing presses, which have always been expensive, to spread those arguments. Does this mean that the rich have more ability to influence public policy than the poor? Yes. Yes it absolutely does.

There is also a question of whether people can pool their resources to create organizations that advocate for certain policies or candidates. The US Supreme Court was recently asked to examine this question and gave an opionion on it, which you can read here: http://www.supremecourt.gov/opinions/09pdf/08-205.pdf