(Reuters) - U.S. stock index futures were flat to slightly lower on Tuesday as investors awaited labor market data, a day after Federal Reserve Chair Jerome Powell pushed back against market expectations for outsized interest rate cuts.

At an economics conference on Monday, Powell reiterated that the central bank is likely to reduce borrowing costs by an additional 50 basis points by year-end, based on data that pointed to robust consumer spending and gross domestic income.

Traders were on the fence regarding the size of the Fed's upcoming interest rate cuts. They are now pricing in a 25 bps reduction at the November meeting with a 62.7% probability, compared with 41.8% a week ago, as per the CME Group's FedWatch Tool.

With inflation nearing the central bank's 2% target, focus is squarely on the labor market as the Fed kicked off monetary policy easing in September.

All eyes are on August's job openings and labor turnover survey (JOLTS) due at 10 a.m. ET, along with the Institute for Supply Management's final estimate for manufacturing activity in September.

"Given that Powell thinks inflation has been conquered, a surprise in the employment reports could still alter the Fed's course," analysts at Rabobank said in a note.

"After all, it's not preset. For example, very poor employment growth or a jump in the unemployment rate could still push the FOMC (Federal Open Market Committee) to make a 50 bps cut."

At 5:34 a.m. ET, Dow E-minis were down 111 points, or 0.26%, S&P 500 E-minis were down 5.25 points, or 0.09% and Nasdaq 100 E-minis were up 15 points, or 0.07%.

Comments from policymakers including Atlanta Fed boss Raphael Bostic, Richmond chief President Thomas Barkin, Boston Fed President Susan Collins and Governor Lisa Cook will be parsed for their insights on the economy and the monetary policy outlook.

Wall Street's three main indexes closed September higher, bucking a historical trend where equities' performance have been weak on average during the month. The benchmark S&P 500 and blue-chip Dow notched their fifth straight month in gains and closed near record highs in the previous session.

Markets also monitored a port strike on the East Coast and the Gulf Coast, halting the flow of about half the nation's ocean shipping. Shares of Designer Brands, Costco, Walmart and CH Robinson were little changed in premarket trading.

CVS Health added 2.3% after a report showed the healthcare firm is exploring options that could include a break-up of the company to separate its retail and insurance units.

Tesla was flat ahead of reporting third-quarter deliveries on Wednesday, with analysts expecting an 8% jump from a year ago.