It HAS to be a spotted salamander.
There are only two venomous lizards in the world, and they are quite large--the gila monster, and the beaded lizard. They live in desert regions, in the far south.
You don't have to worry about lizards being dangerous, none of them are, where you live.
Some newts and salamanders secrete toxins in their skin--so do toads, and some frogs. Don't lick a toad. 
The animal under your porch is harmless, so long as your children don't handle it and stuff their hands in their mouth afterward. Some people experience allergic reactions to spotted salamander toxins, and they are irritating to mucous membranes--most likely the end result would be that your kids would learn not to handle salamanders. It's unlikely to do them any real harm.
Your salamander is probably on its way somewhere else, and chose your porch as a cool waypoint to spend the day. When night falls, it will continue its journey. It is looking for a shallow springtime pond, where it can gather with dozens (perhaps hundreds) of other salamanders, to reproduce. 