Bobert is right. There are plenty of hotels within walking distance to the new Convention Center and I suspect that whoever is sponsoring the conference will have a list. But they are quite expensive and are located in an area that is just now turning the corner from the riots of 68.

The Convention Center is a massive building, encompassing three real city blocks just south west of Mt. Vernon Square. It can be reached by the Metro at the Mt. Vernon Sq. station on the Green Line at the north end, and by the Gallery Place station on the Red Line to the south. Another nearby stop is the Metro Center, which has several connecting lines.

If the conference is big enough to occupy the Convention Center, then most of the hotels will book up quickly. If it is occupying only a portion (my guess) then there should be plenty of room. If you have the time and the budget, I would suggest the Willard (202) 628-9100, which is right next to the White House and down several walking blocks from the Convention Center, or the Hay Adams House (202) 638-6600, just across from the White House. Both of these are historic hotels frequented by Lincoln et al. On a tighter budget, I would go with the Days Inn (202) 842-1020 or the AHY Hostel (202) 737-2333, both near K street, just two blocks north of the Center. Good Luck!