Re: @Chris Parsons -- Russia is a slow-mo failed state
In the United States, lobbying, whether or not one likes it, is rather difficult to describe as "corruption", as it is a constitutionally protected activity. The exact wording, in the First Amendment, is "Congress shall make no law respecting an establishment of religion or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances".
That last phrase legitimizes lobbying and makes it difficult to restrict much beyond making bribery illegal. But that may not matter greatly, as a legislator who takes side payments for exercise of official duties is as corrupt, or more, than one who offers the bribe, but is subject mostly to discipline by other members of the legislature, something that legislators seem loath to do. The Congress also may be disinclined to regulate lobbying (within First Amendment limits) because public relations firms and policy advocacy organizations always are eager to hire former legislators after they retire or their constituents dismiss them. And in the end, it is the voters who decide whether to retain a Senator or Representative because he (or she), possibly corruptly, acts to their collective benefit, or to elect someone new who will do a better job.