The International Monetary Fund is seeing signs of strain in the U.S. economy with fourth-quarter growth likely decelerating from previous forecasts, but a lack of data due to the government shutdown has clouded its ability to assess U.S. economic performance, IMF spokesperson Julie Kozack said on Thursday. Kozack told a regular news briefing that the IMF has delayed its annual "Article IV" policy consultations with U.S. authorities because the shutdown prevented preparatory work, with rescheduled timing not yet set.