Donald Trump: 45 percent

Ted Cruz: 27 percent

John Kasich: 25 percent

Hillary Clinton: 48 percent

Bernie Sanders: 46 percent

Republican presidential front-runner Donald Trump has leaped ahead of his nearest challenger by 18 points, while Texas Sen. Ted Cruz's numbers have plummeted,Trump led Texas Sen. Ted Cruz by only three points one month ago in the same poll.Here are the current standings:In March, Trump was at 41 percent, but Cruz was nipping at his heels at 38 percent with Ohio Gov. John Kasich dragging the bottom at 17 percent.The poll was a survey of 419 GOP primary voters April 11 to 13 and has a margin of error of plus-or-minus 4.5 percent.Cruz was riding a winning wave after securing the Wisconsin primary on April 5, but is not faring as well in upcoming New York, Trump's home state. Trump has been reminding his fellow New Yorkers of Cruz's insult against "New York values" in January when he was angling to win the early voting states of Iowa and New Hampshire.Forty-five percent represents a new high for Trump, according to Fox News. Last month's 41 percent was his previous high. His GOP rivals, including Cruz, had previously claimed his mid-30s numbers were a "ceiling" that he would not be able to rise above when the formerly crowded field began to winnow.On the Democratic side, Vermont Sen. Bernie Sanders is closing the gap nationally against front-runner Hillary Clinton. He trails her by only two points now, up from 13 in March and is within the poll's margin of error.