Pollsters are predicting a big win for Hillary Clinton in Virginia following the entry of third-party presidential candidate Gary Johnson.

According to a new survey by Gravis Marketing, Democratic front-runner Clinton had already been expected to defeat presumed GOP opponent Donald Trump by a slim margin of four points when Virginians go to the polls in November.

But now that former New Mexico Governor Gary Johnson has been nominated to run for president on behalf of America’s Libertarian Party, pollsters are predicting Johnson will now eat away at Trump’s support base in order to provide Clinton with a far more decisive victory in Virginia.

OAKLAND, CA - MAY 27: (L-R) Derreck Johnson, democratic presidential candidate former Secretary of State Hillary Clinton and Oakland mayor Libby Schaaf share a laugh during a roundtable discussion at Home of Chicken and Waffles on May 27, 2016 in Oakland, California. Hillary Clinton continues to campaign in California ahead of the State's presidential primary on June 7th. (Photo by Justin Sullivan/Getty Images)

Last week’s poll quizzed 1,728 registered voters in Virginia via automated phone calls. Registered Democrats formed 36 percent of the survey pool, while 31 percent of those polled were Republicans. Independents formed approximately 32 percent of the sample.

Voters were asked about their perceptions of President Barack Obama, state elections and their thoughts on so-called ‘gay conversion therapies’. Yet above all else, the poll focused on the likely presidential match-up between presumed party nominees Donald Trump and Hillary Clinton.

When asked how they would vote given the choice between Trump and Clinton, 45 percent of voters said they would support for Clinton. By contrast, 41 percent of voters said they would rather support Trump. Approximately 14 percent of voters said they were unsure who to choose, giving Clinton a four point lead. The margin of error for this study was reported at two percent.

That same group of voters were then asked who they would choose to vote for between Clinton, Trump and freshly-crowned Libertarian candidate Gary Johnson. In this scenario, Clinton extended her lead by earning 44 percent of the vote. Trump came in second place with just 28 percent, while Johnson brought in six percent. Around 12 percent of voters said they were still undecided between the three candidates.

BILLINGS, MT - MAY 26: Republican presidential candidate Donald Trump motions to the crowd following a speech at a rally on May 26, 2016 in Billings, Montana. According to a delegate count released Thursday, Trump has reached the number of delegates needed to win the GOP presidential nomination. (Photo by Spencer Platt/Getty Images)

The results of Thursday’s poll represent a relative contrast from a survey published last Monday by Roanoke College.

Roanoke researchers quizzed 610 likely voters in Virginia at the start of May, and found that Clinton and Trump were locked in a statistical dead heat at 38 points each. Approximately 11 percent of those surveyed said they were undecided, while a further 11 percent said they planned to vote for a third-party candidate.

In addition to a hypothetical match-up between Clinton and Trump, Thursday’s poll by Gravis Marketing also quizzed Virginians what they thought about the performance of current President Barack Obama.

When asked whether they approved of Obama, 46 percent said they were happy with his performance. Meanwhile, 47 percent reported they were unsatisfied, and seven percent said they were unsure.

Current Virginia Governor Terry McAuliffe fared about the same – earning an approval rating of 42 percent. By contrast, 40 percent of Virginians said they were unhappy with the Democrat’s time in office.

Nationwide, pollsters paint a slightly more muddled portrayal of a potential Clinton victory come November.

On Thursday, a fresh survey by Rasmussen Reports shaved Clinton’s lead over Trump down to just one point. That left the former Secretary of State well within the survey’s three point margin of error.

Clinton brought in 77 percent of the Democratic vote in that particular survey, versus just 72 percent of Republicans saying they planned to vote for Trump. Each candidate earned 12 percent support from voters in their opposing party.

Independents were split down the middle, with 34 percent claiming they would likely vote for Trump – compared to just 30 percent declaring for Clinton. Around 37 percent of unaffiliated voters said they were either undecided or would prefer to vote for a third-party candidate.

[Photo by Mark Wilson/Getty Images]