>> tonight on c-span, you will hear from supporters and critics of president donald trump during the first 100 days. former u.s. ambassador to germany from the obama administration. the university of california institute of politics hosted the event. here's a preview. >> let's say, we'll probably talk more about this with the iran nuclear deal. but say they do more than what it typically does. what typically does, just so you know is a walk right up to the edge of violating that thing and then we have to pull them back. this happens on a weekly basis. it is a lot of work to keep that deal moving forward as it has been, which is good, but

let's say they violate it. that was a six country deal. you had the chinese, russians, germans, french, the brits and the americans negotiated with the radiance. you've got the other allies, they like the steel. president tromp, who by the way spent a good deal of his transition denigrating the intelligence committee and the quality of the information that they get and spends time saying the press is the enemy and anything he doesn't like his fake news so how will he go to his allies and say we've got intelligence that shows the radiance are violating this agreement and we need to walk it back and re-impose sanctions. you think they will believe him? that's the problem. >> that is a short portion of tonight's program looking at u.s. policy and president donald trump first 100 days in office. to. to see the entire discussion 8:00 p.m. eastern on c-span.

>> a short time ago, army secretary nominee mark green withdrew his name from consideration according to this tweet from the washington post. this comes and mid pass comments he made about gender evolution and islam. he is a state lawmaker in tennessee and a veteran of the iraq war. >> this weekend on american history tv, on c-span three. saturday at eight, lectures in history, college professor on the people and ideas that shape the 1776 pennsylvania constitution. >> the continental congress, the representatives from all of the colonies have instructed after the july 4 declaration, instructed all of the colonies, now states to form new governments. >> sunday at 4:30 p.m. eastern.

secret service and fbi agents reflect on protecting president reagan following the 1981 assassination attempt. >> when i heard shots go off i immediately grabbed my weapon. allie had seconds to determine where the shots were coming from. by that time you saw the smoke from the weapons and individuals moving toward the potential assailant. >> at eight, on the presidency, historian annette gordon reed on the relationship between thomas jefferson and the enslaved hemmings family. >> they thought it was property that could be bought and sold. that was a thing that many members of the family, despite whatever privilege they might have had, they all lived with the specter of the possibility that that could happen because the law construed them as property and jefferson

construed them as property. >> for the complete american history tv schedule, go to c-span.org. >> he once called for the removal of pluto as a planet. on sunday, author and asteroid physicist neil tyson will be our guest on in-depth. >> allow me to tell you that our moon, as miles it was here to earth has five times the mass of pluto. >> so pluto lovers were never told that, were you. so, welcome to the company of informed people regarding pluto. >> during our live three-hour conversation, we will take your calls, tweets and facebook questions was also the director of new york city and welcome to the universe, death by blackhole and his most recent, astrophysics for