Political operatives on both sides of the aisle are closely watching a handful of contests on the presidential, Senate and House levels, bracing for the possibility that a third-party candidate could prove to be a spoiler.

The person whose name comes up most often in these conversations is an obscure former Member, Virginia conservative Virgil Goode. Goode is running for president and has positioned himself to the right of GOP nominee Mitt Romney on fiscal and immigration issues. He is hardly a household name, but the presidential contest in Virginia could come down to a handful of votes. If Goode is able to pull even a few away from Romney, he could be the Republican Party’s Ralph Nader.

“Third-party candidates are an important aspect of individual races every cycle but you cannot predict or make a blanket statement about the way they will play out,” Democratic pollster Anna Greenberg said. “It is very individualized.“

At times, Goode sounds a lot like Nader did in 2000, when he charged that there was no difference between the two major parties and was credited with siphoning the support of enough Democratic-minded voters in key states such as Florida to keep Vice President Al Gore out of the White House.

“It doesn’t matter whether Romney or [President Barack] Obama is elected,” Goode said in an interview about whether he would  push Virginia  into Obama’s column. “There’s not much difference between them.”

Libertarian presidential candidate Gary Johnson has a broader appeal than Goode, but Goode’s small home base in Virginia could prove more consequential.

Downballot, there can be a black hole of information. Polling a third-party candidate can actually boost name identification and overemphasize the candidate’s relevance to a campaign.

“One of the difficulties in polling in races with third-party candidates is that putting them on a poll question gives them more prominence than they usually have in real life,” Democratic pollster Fred Yang said. “And so you’re always weighing how real are these numbers for third-party candidates given there is always a margin of error with every question.”

But because third-party candidates’ numbers are often so low, the margin of error can be deceiving. For instance, if a third-party candidate is polling at 5 percent in an internal poll with a margin of error of 4 points, the candidate could actually be polling as low as 1 percent.

So campaigns will often perform two types of polls — exactly as the ballot will read, and with just the two major party candidates.

Greenberg prefers to test third-party candidates in her polling, not so much in search of the numbers such a candidate will pull, but to look for opportunities to peel off GOP votes or search for dangers for Democrats. Political strategists of both parties generally agree that third-party candidates usually perform better in polling than at the ballot box.

Third-party candidates have cropped up in a handful of targeted Senate races this cycle. In Indiana and Missouri, the Republican candidates have made controversial statements about rape that many find objectionable. The Libertarian candidates in these races offer an outlet for disgruntled  conservatives to park votes without having to vote Democratic.  

In the Montana Senate race between Sen. Jon Tester (D) and Rep. Denny Rehberg (R), Tester allies are actively assisting Libertarian  Dan Cox.

A group with ties to Tester recently aired television advertisements that are critical of Rehberg from a Libertarian bent and include the words: “Vote Cox.”

In the Arizona Senate race, Rep. Jeff Flake (R) was able to fend off a well-funded GOP primary rival thanks to his reputation as one of the most ideologically libertarian House Republicans. But many Arizona operatives are predicting a race down to the wire against former Surgeon General Richard Carmona (D). Libertarian Marc Victor could peel off enough votes to create problems for Flake because his foreign policy positions are less libertarian than his fiscal positions.

At least one Flake source brushed off concerns about Victor, but Carmona sources are watching him closely.

“In a race where there’s high negatives and lots and lots of negative ads, people who get turned off might be looking for a place to put their vote,” the Carmona source said.

Beyond the presidential and Senate fronts, ask almost any political operative about third-party House candidates and most are worried about at least one race where they fear a spoiler effect. Here are some of the races that have raised Republican and Democratic eyebrows:

Arizona’s 9th — Open Seat

Former state Sen. Kyrsten Sinema (D) versus former Paradise Valley Mayor Vernon Parker (R)
Third-party candidate: Powell Gammill (Libertarian)

Iowa’s 4th

Rep. Steve King (R) versus former Iowa first lady Christie Vilsack (D)
Third-party candidate: frequent candidate Martin James Monroe (Independent)

Louisiana’s 3rd — Member vs. Member

Rep. Charles Boustany (R) versus Rep. Jeff Landry (R)
Third-party candidate: There are multiple candidates on the ballot and if no candidate reaches 50 percent, there will be a runoff.

New York’s 24th

Rep. Ann Marie Buerkle (R) versus former Rep. Dan Maffei (D)
Third-party candidate: Ursula Rozum (Green Party)

Michigan’s 1st

Rep. Dan Benishek (R) versus former state Rep. Gary McDowell (D)
Third-party candidates: attorney Emily Salvette (Libertarian) and Ellis Boal (Green Party)

Texas’ 23rd
Rep. Francisco “Quico” Canseco (R) versus state Rep. Pete Gallego (D)
Third-party candidates: Jeffrey Blunt (Libertarian), Ed Scharf (Green Party) and Craig Stephens (Independent)