Hillary ClintonHillary Diane Rodham ClintonChris Murphy’s profile rises with gun tragedies DNC, RNC step up cyber protections Gun proposal picks up GOP support 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 Ann WarrenOvernight Finance: Lawmakers grill Equifax chief over hack | Wells Fargo CEO defends bank's progress | Trump jokes Puerto Rico threw budget 'out of whack' | Mortgage tax fight tests industry clout Michelle Obama is exactly who the Democrats need to win big in 2020 Wells Fargo chief defends bank's progress in tense Senate hearing 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 Antonio RubioOvernight Defense: Tillerson, Trump deny report of rift | Tillerson says he never considered resigning | Trump expresses 'total confidence' in secretary | Rubio asks Army to kick out West Point grad Rubio asks Army to kick out West Point grad with pro-communist posts GOP establishment doubts Bannon’s primary powers MORE (Fla.), Rand PaulRandal (Rand) Howard PaulHouse bill set to reignite debate on warrantless surveillance Authorizing military force is necessary, but insufficient GOP feuds with outside group over analysis of tax framework MORE (Ky.) and Rep. Paul RyanPaul RyanThe Hill Interview: Budget Chair Black sticks around for now Gun proposal picks up GOP support GOP lawmaker Tim Murphy to retire at end of term 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.