Sen. Marco Rubio of Florida took the lead in a second national poll released this week on the 2016 GOP presidential field.

Thirteen percent of respondents in the Fox News poll said they support Rubio, a five percentage point increase since his April 13 presidential announcement, taking him from seventh place to first.

Close behind was Wisconsin Gov. Scott Walker, who received 12 percent support among self-identified Republican primary voters. That's down from 15 percent in March.

Kentucky Sen. Rand Paul followed with 10 percent, former Florida Gov. Jeb Bush and former Arkansas Gov. Mike Huckabee both got 9 percent and Texas Sen. Ted Cruz received 8 percent. Retired neurosurgeon Ben Carson and New Jersey Gov. Chris Christie both got 6 percent.

When GOP candidates were matched up head-to-head against Democratic frontrunner Hillary Clinton, Sen. Paul came closest, trailing by 3 points, 46 percent to 43 percent.

Clinton received support from 62 percent of respondents, while Sen. Elizabeth Warren, who maintains that she isn't running, got 12 percent, and Vice President Joe Biden came in at 9 percent.

A separate poll released by Quinnipiac University this week also found Rubio out front, winning the support of 15 percent of Republican primary voters and faring the best against Clinton in a head-to-head, 45 percent to 43 percent.

In the Fox poll, Clinton was the only candidate deemed dishonest by a majority of respondents, 51 percent, while 45 percent said they thought she was honest. Compare that to the Quinnipiac poll, in which 54 percent of voters said Clinton was not honest or trustworthy, compared to 38 percent who believed she was.

The survey of 1,012 randomly chosen registered nationwide voters occurred from April 19-21 and has a margin of sampling error of plus or minus three percentage points. Results from questions targeting Democratic and Republican primary voters have a sampling error of plus or minus five points.