Drum Up Meaning

Example : 2013 May 25, “No hiding place”[1], The Economist, volume 407, number 8837, page 74:  In America alone, people spent $170 billion on “direct marketing”—junk mail of both the physical and electronic varieties—last year. Yet of those who received unsolicited adverts through the post, only 3% bought anything as a result. If the bumf arrived electronically, the take-up rate was 0.1%. And for online adverts the “conversion” into sales was a minuscule 0.01%. That means about $165 billion was spent not on drumming up business, but on annoying people, creating landfill and cluttering spam filters.  The candidate gave speeches, shook hands, and kissed babies in an effort to drum up support before the election.‎