Listen to "NBC Nightly News," providing reports and analysis of the day's most newsworthy national and international events. This audio podcast, updated each weekday evening by NBCNews.com, brings you the day's show in its entirety. For more from "Nightly News", visit http://www.nbcnews.com/nightly-news
A number of scientists are becoming first-time politicians, many motivated to run for office by what they say is an attack on science by the Trump administration. Chief Environmental Affairs Correspondent Anne Thompson reports.
