So, I've done this quest before on my first play-through and had no issues, but this time I do. I killed the slavers in the Lincoln Memorial before acquiring the Head of State quest, and have successfully completed the quest up to the point of the slaves moving in to the memorial. They perpetually hang out at the entrance to the subway station just down the road from the Memorial. My Pip Boy tells me to talk to Hannibal, but he has nothing available (except I can offer certain Lincoln memorabilia to him). I've tried waiting inside and outside the memorial as well as inside the subway station. The odd part is when I first fast-traveled to the subway station, I did see the slaves start walking - but it was in the opposite direction. I should have followed them, but went off to do something else. When I came back, they were camping out at the entrance to the subway again. So I'm a bit confused.

I've messed around with the console on previous occasions for both Fallout 3, Oblivion, and Morrowind, so I'm perfectly comfortable using commands to set the quest stage or something, but I don't know where to find a list of the quest stages for the Head of State quest (I could just cheat to set it to the next step).

Any ideas would be greatly appreciated.

Ok, so it is becoming stranger. I reloaded to the point where I bring the picture of the memorial back to Caleb and then fast traveled to the Memorial. I met the slaves outside and they started going the opposite way. They actually ended up going INTO a subway station right next to the Museum of History (where the Underworld is). I followed them through the tunnels, taking out the few raiders that showed up and they ended up at the exit to Anacostia Station. Problem is I now CTD whenever I try to leave the subway through that exit. Now I'm really confused.

EDIT:

I found the solution to the problem, though I still don't know the cause. I found the quest ID # and typed "sqs 00014e99" to show the different numbers for the quest stages. I then experimented with the setstage (ID) command and found that stage 60 completed the quest so that the slavers were taken care of. I waited 24 hours and the slaves appeared there; Hannibal then gave me the reward.

So this topic can probably be closed then.

That quest always bugs for me the exact same way. I keep the setstage info handy when doing it. Without fail the past four times I've had to use setstage to finish the quest because Hannibal fails to see I've blasted every slaver from here to The Pitt.

There is a "fix" for this bug: http://planetfallout.gamespy.com/mods/138/Head-of-State-Fix

I had this problem as well. The former slaves kept wandering off in the wrong direction and getting attacked by dogs or super mutants. I reloaded three or four times trying to figure out what was wrong with them and on the third or fourth reload they just started walking in the proper direction and Hannibal's dialog to end the quest triggered there by the metro station. After that everyone very slowly made their way to the Lincoln Memorial.

I don't know if I got lucky or if their wanderings are triggered by other NPCs randomly spawning in the area, but I did notice that when the quest finally worked for me there wasn't a hostile NPC anywhere nearby.

It's easier to use the setstage command to just force the quest script along to the next step.