Politico explores the Senate Majority Leader's victory scenario:

In addition to Reid and the Republican nominee, this year’s Nevada Senate race will include a tea party candidate, four candidates with no party affiliation and a candidate from the Independent American Party, a right-wing party that has more than 57,000 registered voters in the Silver State. 
Reid’s assessment of the race is also based on his own electoral history. In each of his four previous Senate races, third-party candidates and “none of these candidates” combined won at least 4 percent of the overall vote, with the total reaching nearly 8 percent in Reid’s 1992 race against Republican Demar Dahl.
With voters sour on both political parties, third-party candidates could be in a position to garner even more votes than usual this year. The “none of these candidates” option could pull in an unusual level of support as well.

This is an absurd way to win an election. I'd vote for Reid if I lived in Nevada, and don't blame him for playing by the rules as they exist. But this is just another example of the ridiculous nature of electoral rules in the United States. If a majority of the Nevada electorate wants to throw out Reid and replace him with a conservative, they should get to do so, not be foiled because the conservative majority is splintered.