In opening minutes of trading, the Dow Jones industrial average was down 24 points at 13,069. The Standard & Poor's 500 index is down three at 1,411. And the Nasdaq composite index was flat at 2,982.
Investors waited for the Institute for Supply Management's index for service companies, which measures growth at businesses that employ roughly 90 percent of the American work force.
The so-called service sector includes retail and construction companies and health care and financial services firms. It has grown for 33 straight months. Economists expect growth in October at a pace just below September's.
In Europe, renewed focus on the finances of Greece combined with uncertainty about the outcome of the U.S. election to push stocks lower. The benchmark index was down 0.4 percent in Germany, 0.8 percent in France and 0.5 percent in Britain.
The Institute for Supply Management's index for service companies is due at 10 a.m. Eastern Monday and economists are forecasting growth in October at a pace just below what was seen in September.
"With the race so close, investors are understandably risk-averse today," said James Hughes, chief market analyst at Alpari, a London brokerage.
Stocks in Asia finished mostly lower.
(Copyright 2012 by The Associated Press. All Rights Reserved.)