ST. PAUL, Minn. (AP) — Third-party candidates Gary Johnson and Virgil Goode are blips in the presidential race. They have little money, aren't on stage for presidential debates and barely register in the polls — when survey takers even bother to list them as options.

Yet in a tight race between Democratic President Barack Obama and Republican challenger Mitt Romney that likely will be won or lost at the margins, even blips can be a big deal.

Obama's campaign has quietly been tracking the two former Republican officeholders who could be pivotal in key states. Romney's campaign insists it's not worried, even though Republican allies have failed to keep them off state ballots.

Johnson is the Libertarian Party nominee; Goode the Constitution Party candidate.

"At the end of the day this is a two-person race as we're factoring things in like vote goals, turnout," Romney political director Rich Beeson said. "We take it into account, but I can't say I stay up at night thinking about what Gary Johnson or Virgil Goode is going to do."

Johnson, the former New Mexico governor, has qualified for the ballot in 48 states. Goode, a conservative ex-congressman from Virginia, is on ballots in about 25 states. Their standing matters most in Colorado, Iowa, Nevada, New Hampshire, North Carolina and Virginia — states Obama captured four years ago and that Romney has worked feverishly to convert.

In 2008, more than 2 million voters chose someone other than Obama or Republican nominee John McCain. In all but a few states, the winner's margin was so decisive that a third-party bleed-off was hardly worth noting. Obama's electoral college rout made it even less consequential.

This year's race has shaped up to be tighter. It has hallmarks of 2000, when Green Party candidate Ralph Nader drew finger-pointing from the left as a difference-maker between Republican George W. Bush's victory and Democrat Al Gore's loss given the excruciatingly close Florida finish. Jill Stein, this year's Green Party nominee, is viewed as far less of a potential factor than the two right-of-center hopefuls, Goode and Johnson.

With fewer paths to a White House win than Obama, Romney especially can't afford to surrender votes in battleground states.

In Virginia, his biggest threat is Goode, who could bite into Romney's right flank with a campaign appealing to voters who want to stem legal immigration and crack down harder on those in the country illegally. A Baptist with a Southern drawl who held Virginia political office for more than three decades, Goode presents himself as "a real difference between Romney and Obama."

Elsewhere, Johnson is the one to watch, though he could pose difficulties for both major party contenders.

The handyman-turned-politician proudly brags of setting veto records to block spending during two terms as governor. Occasionally donning a peace-sign shirt under his blazer, Johnson has blitzed college campuses with a message aimed at the anti-war, pro-drug legalization crowd that Texas Rep. Ron Paul cultivated in his GOP presidential run. Paul took a respectable share of the vote in Colorado, Iowa, New Hampshire and Nevada.

Paul has yet to endorse anyone in the race, and may not. Meanwhile, Romney has tried to heal fractures between Paul loyalists and the Republican old guard by deploying his former rival's son, Sen. Rand Paul of Kentucky, to campaign events.

New Hampshire state Sen. Andy Sanborn, an adviser to the elder Paul, said Johnson could score with voters at Romney's expense.

"That type of a libertarian candidate will always do well here. I'm hoping frankly that the race isn't close enough that Mr. Johnson will have a material impact in it," said Sanborn, who said he planned to vote for Romney.

Johnson considers himself a headache for both Obama and Romney.

"I'm more conservative than Romney on dollars and cents. I'm more liberal than Obama when it comes to social issues," he said in an interview with The Associated Press.

Johnson's support for gay marriage, eased immigration and a scaling back of government search powers authorized after the Sept. 11 terror attacks make him a wild card in some key states.

One is North Carolina, where Obama prevailed in 2008 by a slim 14,000 votes. Some 40,000 votes were cast for minor party candidates or write-ins, with Libertarian Party nominee Bob Barr getting most of them. Michael Munger, the party's nominee for North Carolina governor the same year, doubted Johnson would have as much of a one-sided effect as the conservative hard-liner Barr.

"I actually think there's sort of a gentleman's agreement about Gary Johnson that neither party brings him up because it takes votes from both sides. In 2008, the Democrats mentioned Bob Barr," Munger said. "They worked to remind people of the fact Bob Barr was in it and real conservatives might want to consider him."

In Colorado, Johnson has aligned himself with a ballot measure to legalize marijuana for recreational use.

Democratic strategist Rick Ridder, a Denver-based veteran of presidential campaigns, said some Democratic activists are supporting Johnson because of his stance on the referendum. But he thinks most voters passionate about making the drug legal to possess will send a message through the proposition itself and make other calculations on the presidential race.

Goode is also on Colorado's ballot. That's notable because two years ago former Colorado Rep. Tom Tancredo finished second in the race for governor under the American Constitution Party's banner.

Johnson, at least, has no problems being labeled a possible spoiler.

"A wasted vote is voting for someone you don't believe in," he said. "Vote for someone you believe in because that's how you change politics."

Copyright 2012 The Associated Press.