Poll: Hillary Clinton, Donald Trump hold on to leads

Washington (CNN)Donald Trump and Hillary Clinton continue to lead their respective presidential primaries, according to a new Fox News poll Wednesday, but Texas Sen. Ted Cruz has closed the gap as candidates have dropped out of the race.

Trump leads Cruz 41% to 38% in the GOP race among likely Republican voters, with John Kasich behind at 17%. But the race has tightened: In February, when candidates including Jeb Bush and Florida Sen. Marco Rubio were still in the race, Cruz was at 19% and Trump 36%.

Recent polls show Trump between 47% and 41% and Cruz between 31% and 26%. This is the only poll that meets CNN standards in which Cruz is polling above 35%.

On the Democratic side, Clinton leads Bernie Sanders 55% to 42% among likely Democratic voters.

As Cruz continues in his efforts to deny Trump from getting to the 1,237 delegates needed to clinch the nomination outright, GOP voters still believe Trump should get the nomination even if he doesn't hit the magic number.

Fifty-nine percent of likely Republican voters said the nomination should automatically go to the candidate with the delegate lead at the convention even if he doesn't hit the majority number, while 35% said the GOP "should have the flexibility to nominate someone else if no candidate has a majority."

Fox News surveyed 1,016 registered voters from March 20 to March 22 for the poll, which has an overall margin of error of plus or minus three percentage points.

That sample included 388 likely GOP voters and 410 likely Democratic voters. Results from each samples have a margin of error of plus or minus 5 percentage points.