honestly, this would help mexico as well.

it would create jobs on either side of the border/canal as ships passing through would likely disembark multiple times between one end and the other.

The ecofascists would of course through a bitch-fit, which is nothing new, but you might even get sane conservationists looking askance at the project, though... =/

edit: The biggest reason i'd be hesitant to support the project is the eminent domain issue...a lot of private property on both sides would have to be siezed, both for the canal and associated support infrastructure and for the construction itself.