nipping at the heels of.
Aggressive dogging or following. It may also be used to mean “catching up to” or “giving negative motivation to.”
The phrase may be genuinely threatening or connote mere annoyance. In his “What's Online?” column, Dan Mitchell states, “For years, David Lazarus, a business columnist for The San Francisco Chronicle, has been nipping at the heels of SBC (now called AT&T), offering a steady stream of caustic criticism.” Lazarus is implicitly more gadfly than attack dog, unable to actually sink his teeth into SBC. However, when Claudia Deutsch wrote that “Canon, which has been nipping at the heels of Xerox in the market for expensive high-speed copiers, is trying to bite chunks out of Hewlett-Packard, Xerox and Lexmark in the market for slower cheaper printers,” her words indicated the threat to Xerox's market share was significant.
1. Safire, William. 1990. Well, Bite My Ankle. New York Times Magazine, Dec 23, 8.
2. Mitchell, Dan. 2006. A Rant. All 406 Pages of It. New York Times, Feb 11, C5.
3. Deutsch, Claudia. 1999. Canon Plans to Expand Its Network of Dealers. New York Times, May 24, C13.