Adam Liptak in The New York Times:
The better approach, Justice Stevens said, would be to allow the government to regulate campaign speech as moderators regulated the recent debates among the Republican presidential candidates.
“Both the candidates and the audience would surely have thought the value of the debate to have suffered if the moderators had allocated the time on the basis of the speakers’ wealth, or if they had held an auction allowing the most time to the highest bidder,” he said. “Yet that is essentially what happens during actual campaigns in which rules equalizing campaign expenditures are forbidden.”
There is nothing wrong with a group of people getting together, raising money and spending it on who they agree with.
It’s the unlimited amount and anonymous nature of the money that is at issue.