In 2018, President Trump hired Rudolph W. Giuliani, his longtime friend and the former New York City mayor, to In 2018, President Trump hired Rudolph W. Giuliani, his longtime friend and the former mayor of New York City, to defend him against the special counsel’s Russia investigation. So how is it that Mr. Giuliani helped get the president entangled in another investigation, this time involving Ukraine?

Our colleague investigated the remarkable behind-the-scenes campaign, encouraged by Mr. Trump and executed by Mr. Giuliani, to gather and disseminate political dirt from a foreign country. Guest: Kenneth P. Vogel, a Washington correspondent for The New York Times. For more information on today’s episode, visit nytimes.com/thedaily.

Background reading:

• The story of a shadow foreign policy in Ukraine unfolded against the backdrop of three elections — this year’s vote in Ukraine and the 2016 and 2020 presidential races in the United States.
• Secretary of State Mike Pompeoconfirmed he listened in on the phone call at the center of the impeachment inquiry.
• Follow our live updates from the investigation in Washington.