Hillary ClintonHillary Rodham ClintonIs it still possible to stop ‘Big Tech’ from killing democracy? Hillary Clinton for 2020 ‘not a good question,’ says Rahm Emanuel Graham: Comey should be held accountable for acting on bad intel MORE has hit a new high in support for a potential presidential run.

Sixty-four percent of Democratic voters surveyed by Democratic firm Public Policy Polling (PPP) support the former secretary of State as the party's nominee for president in 2016, with every other potential candidate trailing by huge margins. Vice President Biden, in second, got only 18 percent support.

Clinton has majority support among every age group polled, nearly every ethnic group and both men and women, as well as a majority of support from liberals and moderates.

But a Clinton run isn't a sure thing, and if she decides against it, Biden's a shoe-in for the nomination, taking 49 percent support to Sen. Elizabeth WarrenElizabeth WarrenSenate panel approves Scott Brown as NZ ambassador Senate confirms Trump's first lower-court nominee The Hill's 12:30 Report MORE's (D-Mass.) 11 percent support. New York Gov. Andrew Cuomo takes 10 percent support, and every other candidate is in single digits.

Clinton fares better than Biden against every potential GOP contender tested, leading all of them by margins ranging from four percentage points to seven.

Among the top four GOP contenders, Biden leads Sens. Marco RubioMarco RubioSenate panel could pass new Russia sanctions this summer McConnell on Trump: 'We could do with a little less drama' Taking the easy layup: Why brain cancer patients depend on it MORE (Fla.), Rand PaulRand PaulSenate gears up for fight on Trump's 0B Saudi Arabia arms sale Paul: 0B Saudi arms deal ‘a travesty’ Senate feels pressure for summer healthcare vote MORE (Ky.) and Rep. Paul RyanPaul Ryan8th graders refuse to take photo with Paul Ryan Dems plot recess offensive on ObamaCare President Trump needs to make some huuuge changes, and soon MORE (Wis.), but by slighter margins than Clinton, and he trails New Jersey Gov. Chris Christie by nine percentage points.

Christie, however, is now in third place among GOP voters in the newest PPP poll.

Rubio maintains his position as the GOP's presidential frontrunner, as he has in every one of PPP's four 2016 polls, holding steady with 21 percent support.

But Paul, buoyed by recent favorable attention surrounding his talking filibuster and straw poll win at the Conservative Political Action Conference, surged in the most recent poll to second place. He now trails Rubio by only four percentage points, up from sixth place with 10 percent support in early February.

Christie comes in slightly behind him with 15 percent support, while Ryan (R-Wis.) and former Florida Gov. Jeb Bush come in fourth at 12 percent. Every other contender received less than 10 percent of the vote.

PPP surveyed 1,247 voters from March 27-30. The poll has a margin of error of plus or minus 3.8 percentage points for the Democratic portion and 2.9 percentage points for the Republican portion.