The International Monetary Fund is downgrading its forecast for the U.S. economy this year because business investment has proved weaker than expected.

The IMF cut its estimate for U.S. economic growth in 2016 to 1.6 percent from the 2.2 percent it had predicted in July.

Its dimmer outlook occurs even as the Federal Reserve is thought to be edging toward a move to raise interest rates in December.

Behind the slump in U.S. business investment, the IMF says, are cutbacks in the energy industry, a strong dollar that is depressing exports and "policy uncertainty" related to the November elections.

The IMF says sluggishness in the United States has been offset by improving prospects among developing economies. It left unchanged its forecast for overall global growth this year at 3.1 percent.