The Democrats are putting a weird spin on this one. The DNC has asked Obama to campaign for certain close races but m as NY of the candidates have asked Obama not to show up. The spin is that they want to take the other candidate on without any surrogate help. Yeah, ok. Since when doesn’t a person running not want help, especially a former president? The fact is, even with his appeal amongst blacks, Obama has been put out to pasture. This guy who was supposed to be this great orator; this great leader; this brilliant guy who knew it all with his Fugazy Nobel Peace Prize was a failure. His eight years in the Oval Office was a disaster. Thanks to Donald Trump people are waking up to fact that Obama was a weak leader. Nations used him as toilet paper. He made horrible deals. It was more that he wanted to be liked then feared ( not what Machiavelli wrote to be a great leader.) Russia and China laughed at him, so did Iran and North Korea.
So when you ask yourself, why wouldn’t Democratic candidates want him, the answer and lies above. Or at least part of it lies above. The other reason is it’s the economy stupid. Under Obama we had very weak growth. Obama continuously blamed Bush. Notice when the economy got strong under Trump he rushed to take credit? We paid obscene prices at the pumps, we got over regulated and people were reluctant to start new businesses. These are a few more reasons why candidates do not want Obama to show up.