NEW YORK, May 7 (Reuters) - Democratic front-runner Hillary Clinton has a higher probability than her likely Republican rival Donald Trump of becoming the next U.S. president, but the gap between the pair narrowed this week, according to the online political stock market PredictIt. Clinton's probability on Friday was 61 percent, down from 65 percent seven days ago, according to the site, which allows users to wager small amounts of money on "yes" or "no" predictions of future events. The probability that Trump will win the Nov. 8 election was 40 percent, up from 34 percent. Trump's sweeping victory in this week's Indiana primary prompted his remaining Republicans rivals Ted Cruz and John Kasich to drop out of the race, cementing the businessman's status as the party's presumptive nominee.