The Democratic National Convention kicks off in Chicago today, less than a month after Democrats changed their nominee in a remarkable political shake-up. To get set for the week, “The Run-Up” talks with Leah Daughtry, an at-large member of the Democratic National Committee, the chief executive of the 2008 and 2016 Democratic National Conventions and a co-chair of the convention rules committee, an incredibly significant role this year given the nominee switch. She is the ultimate Democratic Party insider. And she is also remarkably candid and straightforward, particularly when it comes to providing insight on how party leaders make decisions. Today, a conversation with Ms. Daughtry about how the Democratic Party got to this unusual moment — and what to expect from the convention.