the khan family. >> when i saw donald trump attack another gold-star mother, i felt such a sense of outrage. >> she was standing there. she had nothing to say. >> i would like to tell donald trump what it feels like, the sense of emptiness that only losing a child can bring. >> reporter: trustworthiness still a problem for both nominees. clinton's running mate trying to reassure americans their administration would be more transparent. >> the bottom line is this -- she made a mistake, and she said over and over again, "i made a mistake, and i've learned from it. i'm going to fix it, and i apologize." >> reporter: devin dwyer, abc news, washington. >> one more issue involving donald trump. there's another mexican official who's dismissing trump's promise to build a wall and force mexico to foot the bill. this time it's mexico's foreign minister who called the idea absurd. she said that they would never consider it, and she added that the real issue is not a problem about a wall but a...