The answer, IMHO, is the economic impact of declaring a state of emergency. That's going to send a bigger shock wave thru the market and possibly destroy the presidents chances of being reelected. It's more or less admitting failure to contain or at least get ahead of it when we had the opportunity. Trump isn't very good at taking the responsibility for things when they go south. There's always someone around to fire or become the twitter target of the day. So far that's worked OK for him but I'm not so sure he's going to weather the storm this time. He's been trying to put a happy face on this from the beginning when he should have been sounding the battle stations alarm about 2 weeks ago when we knew it was here.