Idaho election law says a party may remain on the ballot indefinitely as long as it continues to run at least 3 candidates (the package of president, vice-president and electors counts as one). This year, the United Party of Idaho (a centrist party, somewhat like the Reform Party) nominated 3 candidates. However, one of them moved out of his legislative district, and was removed from the November ballot. Therefore, the party only has 2 candidates, not 3.
The law also permits a party to remain on the ballot if it polled for any candidate for federal or state office, a number of votes equal to 3% of the vote cast for governor or president (whichever is on the ballot that year). Idaho has two U.S. House districts. The party is not running any candidates for statewide office, but it has an energetic candidate, Andy Hedden-Nicely, running for U.S. House. Therefore, he needs approximately 6% of the vote in his race, to keep his party qualified for 2008 (since the district includes approximately half of the state, it isn’t enough for him to poll 3%; he needs a vote equal to 3% of the vote cast for Governor in the entire state, yet only half the state can vote for Hedden-Nicely).