Genuine question; Why is he campaigning for re-election in 2020 when he's only been President for a month?
He isn't campaigning. I'm not sure what the coverage is like in England, but here it's non-stop all day long attacks from the media on Trump. There was report by Gallop, I believe, that says on average a new POTUS is given a 7 month grace period before the press really starts to criticize them, ie give them a chance. The attacks on Trump started before he even took office, the media here is just a constant stream of anti-Trump garbage, even stuff that has nothing to do with politics, tech magazines, sports coverage, etc. There wasn't a joke about Obama on a late night talkshow or radioshow for probably 2 years after he was elected.
So the one thing that he said in his press conference that I think was the absolute best point that he made, he said the stuff he is doing (the things that have the press all up in arms, freaking out) is the stuff he said he was going to do during the campaign. He was elected as POTUS to do these things and now he is doing them. He is keeping his campaign promises, something most politicians never do and that, bizzarely, seems awful to them. He has done a lot of good since taking office, he pulled out of the TPP, he has saved and brought back 1000s of jobs, he has started the process to build the wall, he is putting stricter rules in place for letting people in from dangerous parts of the world. Now I understand that you personally, and a lot of other people, might not like some of these things, but those are the things he was elected to do. He does something good and the media spins it as something bad or they just completely ignore it. They talk all day about how the whitehouse is in disarray, but people who work there are saying the opposite. So he decided that if the press isn't going to report fairly and accurately on what he is doing that he will tell the people himself. I think my other favourite part of the press conference, which if you watched he was very calm, and respectfull and having a good time, he said; watch tomorrow, the press will say I am ranting an raving and that headline was printed verbatim in many media outlets.