* Futures down: Dow 54 pts, S&P 4.25 pts, Nasdaq 3.75 pts
By Yashaswini Swamynathan
May 10 (Reuters) - U.S. stock index futures were lower on Wednesday after President Donald Trump's firing of his FBI chief set off a political storm that could make passage of his pro-growth plans more difficult.
* The president said he fired James Comey, who had been leading an investigation into the Trump 2016 campaign's possible collusion with Russia, over his handling of an email scandal involving then-Democratic presidential nominee Hillary Clinton.
* Trump's move added a fresh layer to market uncertainty, which seemed to have eased following Emmanuel Macron's victory in the French election on Sunday. European shares pulled back from 21-month highs on Wednesday.
* Demand for safe-haven assets like gold, bonds and the Japanese yen rose, while the dollar fell.
* Wall Street closed slightly lower on Tuesday after the S&P hit a record high and the VIX hit a decade low.
* Oil prices climbed on the back of a weaker dollar on Wednesday.
* Comments from a couple of Federal Reserve officials, including Minneapolis Fed President Neel Kashkari, will be in focus in the absence of major economic data.
* Snapchat's owner Snap Inc is scheduled to report results for the first time after going public.
* Shares of Nvidia surged 12 percent in premarket trading after the chipmaker reported a better-than-expected jump in quarterly revenue. Shares of rival AMD also rose.
* Allergan was off 1.4 percent at $235.07 after the drugmaker recorded a quarterly loss.
* Yelp tumbled nearly 27 percent to $25.50 following a quarterly revenue miss and disappointing forecast.
Futures snapshot at 6:59 a.m. ET:
* Dow e-minis were down 54 points, or 0.26 percent, with 16,084 contracts changing hands.
* S&P 500 e-minis were down 4.25 points, or 0.18 percent, with 112,753 contracts traded.
* Nasdaq 100 e-minis were down 3.75 points, or 0.07 percent, on volume of 17,642 contracts. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)