19.420—May I approve a transaction with an excluded or disqualified person at a lower tier?
         If a transaction at a lower tier is subject to
 your approval, you as an agency official may not
 approve—
    
    
        
        (a) 
         A covered transaction with a person who is
 currently excluded, unless you obtain an exception
 under  § 19.120; or
    
    
        
        (b) 
         A transaction with a person who is
 disqualified from that transaction, unless you
 obtain a waiver or exception under the statute,
 Executive order, or regulation that is the basis
 for the person's disqualification.