Marco Rubio's lead over Gov. Charlie Crist in the Florida Senate race has grown to more than 30 points, according to a new Public Policy Polling (D) survey.

PPP shows Rubio leading Crist 60-28, including 71-17 among conservatives. It is by far the worst public polling Crist has seen, and casts tremendous doubt on whether he can win the GOP primary.

Self-described "moderates" who are likely to vote in the primary go for Crist 49-36 — an indication of how much better off Crist might be as an independent candidate.

Crist's approval rating as governor stands at just 29 percent among GOP primary voters, who are much happier having state Attorney General Bill McCollum as their nominee. In fact, 56 percent of GOP primary voters say they would prefer Crist didn't run for either Senate or governor.

UPDATE: Crist spokeswoman Andrew Saul responds: "Ultimately, elections are about choices: this election will come down to the choice between an honest public servant with a strong conservative record in Charlie Crist and a Miami lobbyist-politician Marco Rubio, who has traded on his connections for everything from $135 haircuts to fat lobbying deals. Charlie Crist will win this race and win it decisively."