Originally Posted by solbes
You still might want to pitch a pack of dry lager yeast to make sure they yeast are up for the task. But that window is closing fast.
To be honest, I think it's too late. If fermentation has (I'm assuming) started then they are past the reproductive phase and pitching more yeast would be pointless.
I believe any damage that is going to be done already has been done. Yeast reproduce until they are at an optimal concentration for the environment and if they have to work harder (i.e. underpitching) they throw off more off-flavors. And it will probably be worse seeing as they're doing it in 70*F conditions.