Not looking good, the Oct/Nov support has failed (assuming there isn't a rally prior to the close today). Next support for the S+P is 2575 (early April low), and then approx 2550, which was the April closing low (although the actual intraday low was ~ 2535). So that's the general area to watch.
If that key support fails then there are no obvious support levels until you get back to where the breakout began back in 2016 (2100-2200 area). In between would be tentative support areas every 100 points (2500, 2400, 2300, 2200).
Another possibility is that the early 2018 lows hold and there's a series of rallies and retreats, and we spend an extended period in a sideways consolidation. That would be considered healthy considering the huge rally we've had since 2016.
2018 has basically been a 1 year sideways consolidation already. A two year consolidation wouldn't be bad all things considered, similar to the 2 year consolidation from 2014-2016.
Something tells me 2500 isn't going to hold and at minimum there's another couple thousand points of downside to come in the S+P in 2019. Just a guess, but there are a lot of negatives piling up. Fixing the trade/tariff fiasco would go a long way to fixing things. The trade war didn't have to happen at all at this time, other than Trump acting like a bull in a China shop.