WPP CEO Martin Sorrell reported a 7.1 percent rise in first-half revenues to $8.3B on an 11.8 percent jump in pre-tax profit to $987M.

The British company's Hill+Knowlton Strategies, Burson-Marsteller, Cohn & Wolfe, Ogilvy PR Worldwide and RLM Finsbury-led PR/PA group recorded a 4.1 percent profit dip to $92M on flat revenues of $708M.

WPP says its PR/PA group was hit by "continuing client examination of discretionary spending in mature markets."

Sorrell believes American clients, while enjoying record profitability and stronger balance sheets, are reluctant to spend due to uncertainty regarding the $16T U.S. debt load and sequester.

Clients, according to Sorrell, are focused "perhaps unwisely on cost reduction, rather than revenue stimulation and on liquidity, which explains the recent unrealistic request for extended payment terms."

WPP anticipates stronger results in 2014 as global GDP rises four percent, compared to three percent this year.