There's a limit to how far he can fall without Republicans souring on him, and we are probably close to that floor at 38%. I would expect him to hover around 37-42/54-58 territory until he begins bleeding support from his own party. Either way, those are terrible numbers to try and muster support for his administrative agenda.
Once he begins clashing with Congressional Republicans on policy and continues to accumulate scandals and defeats as his term progresses, Republican's will no longer provide him with unanimous support. Losing just 15-25% of his current favorability among Republicans could crater his job approval into the low 30s easily. It will be difficult to reduce it to below 30 and unlikely to occur before the midterms, although I wouldn't be surprised if he consistently registers in the 20s by his last year if his tenure unravels into an absolute free-fall over the years.
Still, anything below 40 percent approval virtually guarantees substantial losses for Republicans in the mid-term, and registering closer to 30 percent by late 2018 could result in a Democratic landslide. Either way, Republicans are stuck with him whether they like it or not.
They're not stuck with him, since Pence would be much better for their party AND the country (and foreign relations). They're just p***ies
