(Bloomberg) — U.S. stock index futures slipped as investors monitored a tight race to determine who will be the next American president.December contracts on the S&P 500 fell 0.6% at 1:25 p.m. in Tokyo. Futures declined 0.4% on the Dow Jones Industrial Average and slid 1% on the Nasdaq 100 Index. Democrat Joe Biden strengthened his hold on the race for the White House, steadily chipping away at Donald Trump’s early lead in a pair of crucial swing states. Trump questioned the credibility of the election.“We had President Donald Trump speaking this morning, bringing back some reminders of the political uncertainty that remains for the U.S.,” said Jingyi Pan, a strategist at IG Asia Pte. “Prices had also been charging strongly and look to be taking a breather ahead of resistance.”Two Republican candidates for Congress in Nevada sued the state’s top election official claiming more than 3,000 votes had been cast illegally, echoing allegations made earlier in the day in Las Vegas by officials with Trump’s campaign. The suit was filed Thursday night in federal court in Las Vegas against Nevada Secretary of State Barbara Cegavske and Joseph Gloria, the election chief in the state’s most populous county.On Thursday, the underlying S&P 500 jumped more than 1% for a fourth consecutive day, heading for the best week since April. The tech-heavy Nasdaq 100 surged 2.6%, pushing its advance this week to more than 9%. Federal Reserve officials kept interest rates near zero while Chair Jerome Powell opened the door to a possible shift in the central bank’s bond purchases in coming months.For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.