Madison was not a supporter at first, but accepted the compromise
and even saw the possibility of some advantages in equal representation among the states. From the Federalist #62:
"Another advantage accruing from this ingredient in the constitution of the Senate is, the additional impediment it must prove against improper acts of legislation. No law or resolution can now be passed without the concurrence, first, of a majority of the people, and then, of a majority of the States. It must be acknowledged that this complicated check on legislation may in some instances be injurious as well as beneficial; and that the peculiar defense which it involves in favor of the smaller States, would be more rational, if any interests common to them, and distinct from those of the other States, would otherwise be exposed to peculiar danger. But as the larger States will always be able, by their power over the supplies, to defeat unreasonable exertions of this prerogative of the lesser States, and as the facility and excess of law-making seem to be the diseases to which our governments are most liable, it is not impossible that this part of the Constitution may be more convenient in practice than it appears to many in contemplation."