[ applause ] raise challenges we face in the future. whether it be over technology, slel electual properly. there isn t a single thing that building a wall can address on any of these issues. as long as donald trump is in the white house, none of these critical things are going to get done. reporter: now biden held back official kickoff rally here in philadelphia, pennsylvania, where he is also basing his campaign headquarters, and it s where biden sees a possible opening. this is a state that president trump won back in 2016. they wanted to bring over to the blue column in 2020. there is a recent poll that showed what a possible head to ho head matchup between joe biden and donald trump would look like with biden beating donald trump 53% to 42%. while biden was here in philadelphia, president trump is coming to the state on monday to