The Goode Effect ?
The Constitution Party nominated Virgil Goode for their presidential nominee on April 21. Goode is probably the most electable candidate the party has ever fielded. They have no office holder on the state or Federal level. In the past the highest number of votes a presidential candidate received was under 200,000 and, since 1992 has averaged about 133,000. To contrast that, the Libertarian Party topped out with the disgraced Bob Barr with over 500,000 votes and averaged about 416,000. The Green Party has done significantly better with Ralph Nader, who received 2,883,105 in one election but without his celebrity they have only averaged about 141,000 votes.
The Libertarians & Greens have done best with better known candidates and this will be the first time the Constitution Party has had a candidate who has actually won an election before. With what party? Pick one. Goode started out as a Democrat in state politics around 1973. After a couple failed bid for the US Senate, he got himself elected to the US Congress in 96, ran as an independent in 2000 & joined the Republican party in 2002 only to join the Constitution Party in 2010.
This election both the Constitution party & Libertarian Party, with Gary Johnson, are fielding previously elected office holders for president. Both stand to get more than a few votes. Couple that with incredible dissatisfaction with both major parties and, without a ringer from the Greens, it looks like Romney has the most to lose.

CLARIFICATION: I only used numbers since 1992 when the Constitution Party started running presidential candidates. The Libertarians actuall garnered almost 1,000,000 votes for Ed Clark in 1980. I lso ignored Ross Perot's run in 1992 where he got 19,741,065 votes because he was kind of a mule in the scheme of things.