Ted Cruz won the GOP primary that allowed him to run for a Senate seat that he eventually won. His campaign failed to report large loans that he received from Wall Street banks to finance his campaign. There was a good reason for the campaign to violate election campaign disclosure laws. He ran as a Tea Party firebrand who opposed the bailout of the Wall Street banks. He and his wife, who was a Goldman Sachs executive in Houston, borrowed large sums against their Goldman Sachs investment account to finance ads that helped him to win the nomination. The campaign also received a large loan from CitiBank which it failed to disclose. If that information were disclosed it would have made it difficult for Cruz to brand himself as a right wing populist who intended to punish the Wall Street banks for their sins.
Campaign disclosure laws are intended to provide information to voters that will help them to make informed decisions when they vote. Politicians like Cruz ignore those laws when they interfere with their branding efforts. They believe that selling the brand to poorly informed voters is more important than conformance to laws which interfere with effective branding.