Obama's approval ratings have jumped because, with Trump and others dominating the news cycle, people are not paying as much attention to him anymore. You ought to recall the way unpopular Presidents, like Bush 43 and Jimmy Carter, quickly enjoyed rising popularity once they left office, showing that absence brings fondness just as "familiarity breeds contempt."
Once Obama hits the campaign trail in full force, he should see his numbers decline.
Yeah, but there's quite a noticeable difference between Bush 43's numbers and Obama's....
I really doubt Obama campaigning will cause the numbers to decline, if anything they should help since he'll be connecting to the public more....his numbers certainly didn't decline when he campaigned in 2012.