"We must reform our immigration system to ensure that it works in an orderly way, that it is humane, and that it makes our country stronger," Kamala Harris tells a campaign event in Arizona -- her first to the border since replacing President Joe Biden as Democratic nominee in July. In her speech, the vice president looks to challenge her Republican rival. "Even though Donald Trump tried to sabotage the border security bill, it is my pledge to you (...) I will bring it back up and proudly sign it into law," Harris says. IMAGES AND SOUNDBITES