Tricks for disrupting large AI empires?

[King's Specter]

OK, last one of the day... :)

I'm playing a large disc galaxy and am into turn 220 or so. Once I complete my assimilation of some smaller empires, I'll end up with about 40% of the galaxy. The next two smaller empires (which are allies) will have about 60% of the galaxy combined.

What are the best ways o softening these two up before I go to war with them. Is there a good method of breaking their alliance before I attack one of them? Are spys good at causing bad relations or causing revolts?

Right now, there are only two empires in the senate (myself and a tiny empire), I can dominate the votes. Is there anything I can do with the senate to hurt either of these outsider empires? The new orions have already kicked the smaller of the two out of the senate and are at war with them (but don't seem to be doing anything).

[James1701]

Scrape up a decent sized force out of your older ships and find a place (if it exists) where you can offroad to planet away from there borders.

I usually move into their empire at least one system from my entry point just in case I have to retreat so I don't get bounced right back out into the void.

After that, hit a planet, move on to a different system, hit a planet, move on to a different system, wash, rinse, repeat.

This is quite effective against the AI as they aren't very good about anticipating where you are GOING to be, only where you ARE.

I use this tactic quite a bit when I need to take a rival AI empire down a peg or two but I'm not in a good position to invade directly. Of course the trick is to keep moving so they don't mobilize a fleet right on top of you.