(CNN)The main super PACs supporting Texas Sen. Ted Cruz's presidential campaign only raised a few million dollars in the second half of 2015, a modest sum that far trails the huge checks they collected in the opening days of the campaign. Cruz's super PACs, Keep the Promise, have raised only around $2 million in the second half of 2015, according to two people familiar with the figures. The groups have raised up to $5 million in the month of January, the sources said. That's a far cry from the $38 million raised in the first half of 2015, most of...