How do you create characters? Also,can you sim multiple turns at a time?
Assuming you're using President Infinity and not an older version, there should be a campaign editor that will allow you to add a new party and leader. If you do it that way, then all you should need is to open that editor and create a new party in the "parties" tab, then make sure to lower any stats/bonuses of the party to 0 or the lowest alternative. Then go to the "leaders" and customize the base candidate to have 1/1/1/1/etc. stats, no money (unless you want the option to influence things, some people call this an "Illuminati" party rather than observer), no region bonuses, etc. Ben Franklin doesn't need to be involved but that does seem to be the trend, however the images and name you choose for the party/leader are purely cosmetic, the stats make the difference.
Other good tips are to reduce any party percentages in the regions to 0, and there should be a box on one of the screens that has an "on ballot" check box, turn this off for you observer party. There shouldn't be any, but check the endorser tab to make sure no endorsers are set to favor your party/leader.
A good example of a de facto observer party that doesn't look like on is in the scenario in 1868 or a little later with the Equal Rights party. Led by a woman before they could vote (and I believe she was under 35 as well) she is a candidate with stats but no ballot access, so 0 votes unless the player fights for ballot access.
If you don't have/ can't use the built-in editor, you could copy the scenario you want to make/modify and tinker with the files in notepad. I would open file explorer twice, split screen, the scenario I'm customizing on one side and a scenario with a working observer party in the other. Then just use Notepad or an equivalent to open/edit the files in the custom scenario, searching the original for any mentions of an observer and copying that code over.
On mobile but I can demo this further and am happy to help. One last note, save and test often no matter what method you use. Too many big changes can leave you with mistakes that are a pain to roll back and I've restarted scenarios to get around errors. Don't hesitate to copy your working but unfinished file before making changes, you can always revert that way.
As far as multiple turns, there is an option to advance 7 days with each press of the space bar, but you still see the popups and news each day, its not a case of pressing the button once and being a week ahead.