some of the cent rift democrats and independents with just pushing medicare for all. >> reporter: while warren has taken a dip, buttigieg has been gaining. surging to the top of the field in iowa for the first time last month. the two candidates trading barbs over the last week on political transparency. warren calling on buttigieg to make his fund-raisers open to the press and disclose his past consulting clients. buttigieg demanding that warren release more of her tax returns going back decades to when she did legal work for corporate clients. both candidates ultimately making new disclosures about their work in the private sector. warren reacting tuesday night to buttigieg revealing his client list. >> one of those clients was blue cross blue shield in michigan. what is your reaction to that? >> i am glad the mayor has taken these steps. i think it is really important that as we go into the 2020 election that we have the best chance to win against donald