Welcome to Trail Guide, your daily tour along the road to the White House. It's Sunday, Aug. 30, and this is what we're watching:
- A new poll in Iowa shows Hillary Rodham Clinton up 37% to 30% over Sen. Bernie Sanders
- Scott Walker, fresh off a foreign policy speech in South Carolina, joins NBC's "Meet the Press"
- Ted Cruz begins the first day of a two-day swing through New Hampshire
- What's Donald Trump saying on the Sunday shows? We'll have the best of his quotes