WASHINGTON (Reuters) - U.S. Democratic presidential candidate Hillary Clinton led Republican Donald Trump by 6 percentage points among likely U.S. voters in a Monmouth University poll released on Monday, a day before the U.S. presidential election. The survey of 802 registered voters found 50 percent backed Clinton while 44 percent supported Trump, with a margin of error of plus or minus 3.6 percentage points, the university said in a statement. Its last poll released on Oct. 17 found Clinton up by 12 points, it said. Several other national opinion polls released earlier on Monday showed Clinton with a 3-point or 4-point advantage. 