Money is property; it is not speech. Speech has the power to inspire volunteers to perform a multitude of tasks on a campaign trail, on a battleground, or even on a football field. Money, meanwhile, has the power to pay hired laborers to perform the same tasks. It does not follow, however, that the First Amendment provides the same measure of protection to the use of money to accomplish such goals as it provides to the use of ideas to achieve the same results.

Concurring, Nixon v. Shrink Missouri Government PAC, 528 U.S. 377 (2000)