Source: https://www.nytimes.com/2016/01/31/nyregion/de-blasio-arrives-in-iowa-to-help-hillary-clinton-in-last-push-before-caucuses.html?rref=collection%2Fsectioncollection%2Fnyregion&action=click&contentCollection=nyregion®ion=rank&module=package&version=highlights&contentPlacement=2&pgtype=sectionfront