* ADP payrolls report slightly stronger than forecast * ISM report on service sector due at 1400 GMT * Focus on employment component of ISM report * Market mainly waiting for U.S. payrolls data due Friday By Ellen Freilich NEW YORK, Oct 3 (Reuters) - U.S. Treasuries prices slipped on Wednesday after a stronger-than-forecast labor market report and before a widely followed report on the nation's service sector. Payrolls processor ADP's report that U.S. private employers added 162,000 jobs in September, topping economists' forecasts, weighed on bond prices. The impact was not dramatic, though, because the report has not been a good immediate predictor of job growth as reported by the U.S. Labor Department each month. "The market reaction was muted," said Eric Stein, vice president and portfolio manager at Eaton Vance Investment Managers in Boston. "ADP is a pretty good indicator for helping to analyze the labor market, but it has not done a very good job of predicting the subsequent (U.S. Labor Department) payrolls print so many short-term traders give it less weight." The benchmark 10-year note was down 1/32, leaving its yield at 1.63 percent, in the middle of its recent range. Jim O'Sullivan, chief U.S. economist at High Frequency Economics in Valhalla, New York, said the data suggested about a 155,000 rise in total payroll job growth as figured by the U.S. Labor Department. That tops the current consensus forecast, drawn from a Reuters poll, of 113,000 new jobs for September. The market's next immediate focus is the Institute for Supply Management's September report on the non-manufacturing sector, due at 10 a.m. EDT (1400 GMT). Economists polled by Reuters look for a reading of 53.2, slightly below the August reading of 53.7. Any reading above 50 points to expansion. The market will pay attention to the employment component of the non-manufacturing ISM survey since it could influence expectations for the U.S. employment data due this Friday. Treasuries could tend to play defensive ahead of Friday's payrolls number, some analysts said. "Strong car sales, an improving housing sector and further signs hiring is gradually picking up work against bond bulls," said Josh Stiles, director of research at IDEAglobal in New York. "That all tends to favor (President Barack) Obama's re-election just as the debates are about to begin and leaves dealing with the 'fiscal cliff' as the key policy action later in the year."