Gov. Rick Scott and Charlie Crist are essentially tied 37-39 percent in Florida's hotly contested governor's race, partly because a little-known Libertarian candidate is sapping support from the Democratic challenger, a new poll indicates.

Libertarian Adrian Wyllie pulls 9 percent support, according to Quinnipiac University's survey, which shows Crist's 2 percentage-point lead would grow to 5 points without Wyllie on the ballot.

The close race between the frontrunners is a marked improvement for the unpopular Scott since Quinnipiac's April survey. The results also underscore the power of the Republican's mammoth $18 million ad campaign, which has damaged Crist and boosted Scott.

Little-polled until now, Wyllie's name appears to be an emerging and significant factor in the race.

"Wyllie is not, at this point, a serious contender to win the governorship. But he may have a great deal to say about who does win," Peter A. Brown, assistant director of the Quinnipiac University Poll, said in a written statement.

With Wyllie on the ticket, Crist loses more support among self-identified independents (9 percentage points) than Scott (4 points). Independents comprise about a quarter of Florida's vote.

From supporting medical marijuana to opposing most abortion restrictions, Wyllie's stand on social issues is closer to Crist's than Scott's. Wyllie has been more vocal than Crist about supporting a popular prescription-marijuana measure on the ballot — even though the push for the measure is largely funded by Crist's employer, Orlando trial lawyer John Morgan.

"Virtually no one knows much about Wyllie," Brown said, referring to the 92 percent of voters who had no opinion of the Libertarian. "But there are a lot of Floridians who aren't keen on either of the major party candidates."

Voter rolls tell a similar story. More people than ever are signing up to become voters who have no-party or third-party affiliation.

One of the worst numbers for Scott in the poll: 51 percent of voters say he doesn't deserve a second term; 40 percent say he does.

By the same 51-40 percent spread, voters said Scott is not honest and trustworthy. The difference, or "index," is -11.

Crist's honesty index is -9.

In the context of Scott's historically poor poll numbers, the latest survey has some good news for the embattled incumbent. He's marginally improving his poor standing across the board — and he is dragging Crist down by a slightly greater degree at the same time.

It didn't come cheap.

Scott and the Republican Party of Florida have spent about $18 million on TV ads since Crist entered the race in November. Of that, more than $12 million was spent unanswered until early June, when Crist and the Florida Democratic Party pushed back with what now amounts to about $4 million in ad spending.

The Republican Party of Florida on Tuesday released a Spanish-language ad promoting Scott's education spending; Crist followed up with his own education-themed English-language ad Wednesday that attacked Scott's school spending.

During the time Scott owned the airwaves alone, he had a free hand to negatively define Crist and positively define himself without any paid-media response. The strategy resembled the early, negative campaign that President Barack Obama waged against Republican Mitt Romney in 2012.

Crist still edges Scott overall in measures of likability, compassion and caring in the poll of 1,251 self-identified registered voters, which has a 2.8 percentage-point error margin.

But the underlying trends in Quinnipiac's polling since April favor Scott:

Strong leadership. By 54-38 percent, voters say Scott is a strong leader compared to Crist's 49-43 percent. That's close to the opposite of the April findings. Scott's index has moved 11 percentage points in the governor's favor, Crist's index has moved 12 points to his detriment.

Truthfulness. Crist took a notable hit in appearing honest and trustworthy. His -9 index (39-48 percent) is down from a +2 index in April. That's a net 11-point shift. Scott's index is about the same.

Favorability. Only 40 percent have a favorable impression of Scott and 45 percent an unfavorable impression. But his -5 favorability index is an all-time high and a two-point improvement since April. Crist's 40-42 percentage favorability spread is an all-time low; a -2 index that represents a 9-point shift to his detriment.

Job approval. Scott's anemic 43-48 percent job-approval numbers is his best ever. The -5 index represents a three-point shift in his favor since April.

Compassion and caring. Does Crist care about voters? More say no than yes now. His index is -3, a 9-point shift against him. Scott's index is worse: -11. But that's an improvement from -17. Crist is seen as more compassionate than Scott by 12 percentage points, but the spread is three points smaller than it was in April.

Head-to-head lead. Leaving out Wyllie, Crist's 5-point lead of 45-40 percent has been cut exactly in half from his 10-point, 48-38 percentage lead he had in April.

The poll has far worse news for little-known Democrat Nan Rich, who faces Crist in the Aug. 26 primary. She's losing to Scott head to head by a 42-36 percent margin.

One of Rich's lines of attack against Crist — his switching from Republican to independent to Democrat —yields mixed results in the poll; 47 percent view the party-switching positively and 45 percent see it negatively.

Scott's effort to tie an unpopular President Obama to Crist, who helped the Democrat win his 2012 re-election in Florida, might be even less effective. Asked if a vote for governor was a vote for or against Obama, respondents were evenly split at 16 percent, but 65 percent said it made no difference.

The poll sheds no light on Crist's decision last week to name Miami-Dade Democratic Party Chairwoman Annette Taddeo to his ticket.

Another poll, conducted by SurveyUSA for Tampa-based WFLA-TV and released Tuesday, indicated Crist might have picked up support, however.

SurveyUSA found that Crist leads Scott 46-40 percent without Wyllie on the ballot — nearly identical to Quinnipiac's results, sans Wyllie. The SurveyUSA findings also indicated the Democrat regained the nominal lead in the race after trailing Scott in an early July poll.

The five-day survey was coincidentally started the day Crist picked Taddeo and amid some of the worst local TV news coverage of Scott, which featured the governor dodging and avoiding numerous questions on stations from South Florida to Tampa Bay.

SurveyUSA pollster Jay Leve, however, attributed a good chunk of Crist's movement to the Taddeo pick.

"The news after-glow for Crist has continued for about five days," Leve said.