NYT:

But as the fall campaign unfolds, voters in states like New Hampshire and Iowa have been left largely in the dark about who is putting the most money behind Mr. Rubio. Of all the television advertisements aired in support of the Florida senator so far this year — $5.5 million worth — none have been paid for by Mr. Rubio’s own campaign. Even the “super PAC” supporting him has not yet spent a dime on ads.