I think one needs to blame the First Amendment for this, not lobbyist. If I want to put up billboards advocating for a given politician, that is fully in my right. That I rent the space on the billboards to others and they use it to advocate for a politician isn't a significant difference. Even if we were to say that speech cannot be sold, then all that does is force the contract to become a bit different (instead of me renting the space, I sell it to the one putting up the adds with a promise to sell back or a certain fiscal penalty if I don't).

At the core of this problem is that speech can be amplified with money. Even if we ban selling of speech to others, organizations can still spend the money to host/print/post/billboard/telecast their own messages. Those with money will out message those without.

Is there a way to fix this that doesn't result in government control of political speech?

>I think one needs to blame the First Amendment for this, not lobbyist.

The first amendment has only been loosely upheld throughout our history. There are many types of speech that are regulated in spite of it.

>Is there a way to fix this that doesn't result in government control of political speech?

We had a system in place prior to Citizens United that didn't turn into government control of political speech. Many other developed countries have limitations on spending money on political speech that don't turn into complete government control of political speech.

There's no reason to assume that a few men in the 1780s got everything right. And a slippery slope argument is no reason to throw up our hands and stop trying to advance egalitarianism.