Same way branches of the Federal Government delegates responsibilities and procedural obligations to the appropriate agencies.
I honestly cannot understand how companies have any representation or access to politicians. The closest access to the system should be persuading their own employees to vote favorably or write their congressman. Lobbying should be entirely illegal because we are on track to making Idiocracy a reality.
It would be pretty difficult to restrict lobbying without running into problems with the First Amendment.
Most people who complain about corporate lobbying don't seem to mind when the EFF or the ACLU engages in lobbying, which indicates to me that they are really against corporate power, not lobbying per se.
Then fuck the first amendment. Change it.