Article snippet: William Taylor, the United States’ top diplomat in Ukraine, testified Tuesday that President Trump was holding back military aid for Ukraine unless the country agreed to investigate Democrats and a company linked to Joe Biden’s family, providing lawmakers with a detailed new account of the quid pro quo central to the impeachment probe. In a lengthy opening statement to House investigators, Taylor described Trump’s demand that ‘‘everything’’ President Volodymyr Zelenskiy wanted, including vital aid to counter Russia, hinged on making a public vow that Ukraine would investigate Democrats going back to the 2016 US election as well as a company linked to the family of Trump’s potential 2020 Democratic rival. Read Taylor’s opening statement: Material from the Associated Press was used in this report. Digital Access Home Delivery Gift Subscriptions Log In Manage My Account Customer Service Help & FAQs Globe Newsroom Advertise Newsletters View the ePaper Order Back Issues News in Education Search the Archives Privacy Policy Terms of Service Terms of Purchase Work at Boston Globe Media Link to the full article to read more