Four Republican presidential candidates lead Hillary ClintonHillary Diane Rodham ClintonIntel Dem decries White House 'gag order' after Bannon testimony 'Total free-for-all' as Bannon clashes with Intel members Mellman: On Political Authenticity (Part 2) MORE nationally in head-to-head match-ups, according to a new poll.

The Fox News survey released on Tuesday shows Ben CarsonBenjamin (Ben) Solomon CarsonTrump must pair more respectful rhetoric with positive policies Trump honors MLK amid firestorm over racially charged remarks Reporter asks Trump 'Are you a racist?' after MLK event MORE running the strongest against Clinton, with the retired neurosurgeon taking 50 percent, compared to only 39 percent for the former secretary of State.

Donald TrumpDonald John TrumpDems flip Wisconsin state Senate seat Sessions: 'We should be like Canada' in how we take in immigrants GOP rep: 'Sheet metal and garbage' everywhere in Haiti MORE leads Clinton by 45 percent to 40, Jeb Bush leads Clinton 44 to 40 and Carly Fiorina leads Clinton 42 to 39, the poll found.

While it can be dangerous to read too much into any poll this early in the presidential contest, the Fox News survey wil give ammunition to those arguing that Vice President Biden would be a stronger Democratic candidate than Clinton. 

Biden leads all of those same Republican contenders in head-to-head match-ups. He's up on Trump by 50 percent to 37, Bush by 46 to 41 percent and enjoys leads of 46 to 42 percent over both Carson and Fiorina.

Sen. Marco RubioMarco Antonio RubioOvernight Cybersecurity: Bipartisan bill aims to deter election interference | Russian hackers target Senate | House Intel panel subpoenas Bannon | DHS giving 'active defense' cyber tools to private sector Senators unveil bipartisan push to deter future election interference Puerto Rico's children need recovery funds MORE (R-Fla.) does the best in a head-to-head match-up against Biden, trailing by only one point, 44 to 43 percent.

In previous polls, Clinton held leads over all of those candidates except for Bush, who led 44 to 42 percent over Clinton in an August poll.

The Fox News survey also provides new evidence underlying Carson’s early strength.

Carson raised $20 million in the second quarter, which will likely be the biggest haul of any of the GOP contenders. He routinely attracts thousands of supporters on the campaign trail and is firmly in second place in polls of the Republican presidential nomination, trailing only Trump.

The poll found Clinton maintaining a healthy lead in the race for the Democratic presidential nomination, taking 45 percent support, followed by Sen. Bernie SandersBernard (Bernie) SandersMellman: On Political Authenticity (Part 2) Former Sanders campaign manager: Don't expect email list to be shared with DNC Adult film star: Trump and Stormy Daniels invited me to 'hang out' MORE (I-Vt.) at 25 percent and Biden at 19 percent.

That’s a bigger lead for Clinton than in the same poll from September, when the former secretary of State took 44 percent support, followed by Sanders at 30 and Biden at 18.

Biden has yet to decide whether to enter the race.

The Fox News poll of 1,004 registered voters was conducted between Oct. 10 and Oct. 12 and has a 3-percentage-point margin of error.