Former President Barack Obama has preferred to keep a low profile since departing the White House, continuing the (perhaps flawed) bipartisan tradition of past presidents demurring when asked to weigh in on their successors. That's not to say he hasn't been lending himself to Democrats contemplating taking Trump on themselves, however.
He has counseled more than a dozen declared or likely candidates on what he believes it will take to beat President Trump, holding private talks with leading contenders like Ms. Harris, Mr. Booker and Senator Elizabeth Warren; underdogs like Pete Buttigieg, the mayor of South Bend, Ind.; and prominent figures who remain undecided on the race, like Eric H. Holder, his former attorney general, and Michael R. Bloomberg, the former mayor of New York.
Obama's advice, at least according to the New York Times, has been to avoid intraparty battles and to push back on Trump's "divisive" rhetoric with messages that even rural and other Trump-leaning voters can get behind. This is certainly how Obama himself chose to run and govern, so it makes sense that he would push would-be contenders to follow the same path. What he is not offering, and is not expected to offer, is an endorsement of a particular candidate, instead preferring to let primary voters make that decision. The candidate that might make the most difference to is former Vice President Joe Biden, who might have been hoping for that particular boost-up.
Not much can be gleaned from the rest of the Times' report. Obama has words of praise for a number of candidates, including some distant long shots. Some unnamed Democrats appear to be unsatisfied with his reluctance to weigh in on behalf of a specific contender, which we might take as a hint that some fundraisers are still pining for a more "moderate" candidate that will not upset the apple cart as roughly as the Democratic base itself is pushing for. It is impossible to read too much into such reports because, yet again, early campaign coverage of this sort tends to focus excessively on what individual behind-the-scenes strategists and functionaries want to see reported.
There is indeed a school of thought inside the Democratic Party that tends to get nervous in the vicinity of big ideas, and downright hostile to big ideas that stand in opposition to the dozen or so of the nation's most generous business interests. That notion was ascendent in the party for decades—and a good number of its “Blue Dog” adherents got their behinds handed to them in the recent political restructurings, which saw the ideological divide between the two parties grow into the current stark partition. It is not clear whether such theories have much remaining sway with the actual voters who will decide these things, no matter how much money is spent to convince them.
So what you can read from this is that Barack Obama has been graciously offering advice to any Democratic contender who requests it; that he's not intending to play a large role in the primary process itself or pre-endorse a given candidate; and that a lot of different people have a lot of different ideas on whether that's good or bad or indifferent or whatever. That sounds about right. And if that situation changes, we'll let you know.