President Obama has never shown must interest in campaign for other Democrats and it has now gotten to the point that even if he wanted to he would probably end up doing more harm than good.
Not only has Obama’s approval rating been negative for almost a year but the number of people excited about him has also plummeted. The percent of people who strongly disapprove of Obama is now more than double the number who strongly approve of him. From Gallup:
Obama campaigning in a swing state or swing district could end up doing more to rally Republicans than it would to rally Democrats, so don’t expect him to make many stops which aren’t fund raising.
Any victories by Democrats this year will be mostly in spite of Obama, not because of him.