U.S. stock index futures were lower on Tuesday, as investors awaited a crucial labor market report, while fretting over likely delays in the release of key economic data due to a potential government shutdown. "However, the length of any shutdown can impact the collection and release of important economic data, especially at a time when the economy is at a crucial juncture with regard to growth and inflation." ET, Dow E-minis were down 131 points, or 0.28%, S&P 500 E-minis were down 15.5 points, or 0.23%, and Nasdaq 100 E-minis were down 54.75 points, or 0.22%. Markets will now enter the fourth quarter, historically a favorable stretch for equities due to year-end positioning and holiday spending. Nike is scheduled to report earnings after markets close on Tuesday, offering an early look at consumer demand and margin trends.