George, I think I know what you're facing. My wonderful aunt (age 80) is one of the great Tomato Soup burners of all time! I thinks it's a hobby.
Anyway, I have found that a couple of things have worked for me, but they both require A LOT of patience. One is to squirt a GENEROUS amount of some product like Soft Scrub W/ Clorox Bleach over the mess, and then put very wet towels on top of that (the hotter you can handle the water, the better). You'll have to leave them there for quite a while and make sure they stay good and wet (I've even covered the towels with alumninum foil and left them overnight). Of course, you'll want to be careful you don't cover a standing pilot light... we don't want to add a house fire to your troubles. The moisture and cleaner do eventually soften the mess quite a bit and that helps with the next step.
Using a BLUE Scotch Brite sponge with a scrubber pad (don't use the green ones, they're too harsh) in conjuction with more of the Soft Scrub W Clorox Bleach, start seeing if you can get the now softened food off the porcelain. I have occassionally resorted to using a single edge razor blade, but you can knick the porcelain with this, so go very slowly.
Perhaps someone else will have a better/easier solution (and I would be the first one who would LOVE to hear it!), but this is what has worked for me. Mostly elbow grease. When you are all done cleaning up, if you have any energy left at all, you might apply a coat of appliance polish (available at any hardware store). I have found that this polish does help to release the next overflow of Tomato Soup a little more easily.