Final answer:
Lewis and Clark's expedition faced primarily logistical challenges, including difficult weather, navigation, interactions with wildlife, and relations with Native American tribes.
Step-by-step explanation:
The difficulty facing Lewis and Clark was primarily logistical in nature. During their expedition, they encountered a range of challenges such as harsh weather conditions, unfamiliar terrain, encounters with various wildlife, and the need to establish peaceful relations with Native American tribes. While there were financial aspects involved, the logistical aspects included everything from navigation, dealing with the natural elements, and ensuring ample supplies for the journey. Political challenges were also present, including asserting U.S. claims to the new territory against other powers such as Great Britain and Spain, but these were more of a background issue related to the expedition's purpose rather than immediate day-to-day difficulties.