012820 304 The Democratic Candidates for president are making a last-minute push across the state of Iowa less than a week before the first-in-the-nation caucuses. A few more challengers have announced plans to visit Sioux City. Tomorrow, former Vice President Joe Biden will hold an event at Western Iowa Tech Community College. He will appear at the Rocklin Center at 1:15 p.m. A previous appearance by Biden earlier this month was canceled because of bad weather. Minnesota Senator Amy Klobuchar