"...believes could challenge President Donald Trump for reelection — or are likely to run if he does not" Opposition research is like an AK-47: Better to have it and not need it than need it and not have it.
While I think that the possibility is exceedingly low that anyone serious will challenge the President in the 2020 Republican primaries, apart from some unknown and entirely-token 'never-Trumper' perhaps, the Democrats probably do need to think about and make some preparations for the possibility. I don't fault them for that. Of course, their own Presidential primaries will be wide open in 2020 and that's where a full-scale battle is apt to break out. The future of the Democratic party will be up for grabs. There's a formerly ascendant moderate Democratic faction composed of Hillary's DNC and the Congresspeople and Senators who need to run for reelection in states Trump won, there's a Bernie-ite old-style socialist faction, there are all manner of sometimes single-issue race, ethnic and "gender" activists, there are all the left-wing celebrities, the campus radicals and even the 'antifa' crazies. The Democrats are a very loose coalition of often monomaniacal self-interested identity politics. Their attempts hold everything together and get it all going in one direction will be interesting to watch.
Personally, I don't think they have any idea of what they're doing and if they had an idea, it would probably be a stupid idea.
