Based on the quotations provided, the writer who most likely supported Jackson is the newspaper editor.
Which writer supported Jackson?
The newspaper editor thinks highly of Jackson and his supporters. The editor thinks the inauguration is a happy and exciting day for the people, showing that they are proud of Jackson becoming the president. The editor calls General Jackson "their own President," showing that the people feel like they own and support Jackson.
In addition, the editor said that people were very happy to see Jackson and thought of him as a hero because he had achieved something great. This shows that the editor thinks Jackson has won something important and has a lot of public support.