US stock markets settled lower on Tuesday as investors weighed quarterly earnings and a possible delay in tax reforms, while keeping an eye on global politics.

U.S. Treasury Secretary Steven Mnuchin told the Financial Times on Monday that the Trump administration's timetable for tax reform was probably delayed following setbacks in negotiations with Congress over healthcare.

The Dow Jones Industrial Average fell 113.64 points or 0.55 percent to settle at 20,523.28. NASDAQ 100 index lost 7.54 points or 0.14 percent to close at 5,391.66. The broader S&P 500 index declined 6.82 points or 0.29 percent to end at 2,342.19.