Theodore Roosevelt wanted to build a canal in Central America. Why was there opposition to Roosevelt's plan?

Answer 1

There certainly must have been some opposition in Colombia, since the land where the canal was built was taken away from that country and given to Panama.

Since a previous attempt to build such a canal by France failed, there must have also been some opposition to the cost as well.

Those are answers off the top of my head. I suggest you do a search and read some references on the subject.