The 24-70/2.8 has a macro range and focuses quite close. I don't know the exact specifications (you can look it up on Canon's website), but it's not very short of the 1:2 you are looking for. Perhaps a 12mm or 25mm extension tube would put you into the ballpark.
The fact that you indicate wanting a standard zoom made the 24-70 my first recommendation. Yes, any of the 70-200 also work pretty well with extension tubes, too. You will need longer tubes to get higher magnification, or a set and two or more tubes stacked.
Back to the standard zoom, I'd look at the 17-55 IS and see how close focusing it is, too. Keep in mind that you can use extension tubes behind practically any lens, to make it close focusing and increase magnification.