Scott Conroy, a national politics reporter for Real Clear Politics, has this article about why it is so difficult for a new political party in the United States to take root, even when there is widespread antipathy for each of the two older major parties. Conroy was a network TV reporter in 2012 who covered the Mitt Romney presidential campaign full-time.
The analysis says that given the U.S. winner-take-all system, combined with a separate election for president (as opposed to a parliamentary system), it is virtually impossible for a new party to arise. But this ignores the fact that in the 19th century, when the United States had the same election structure, three times one major party died off and was replaced by another. The Federalist Party died after 1820, to be replaced in 1825 by the National Republican Party (which ran John Quincy Adams for president in 1828, and Henry Clay in 1832). The National Republican Party died off and was replaced by the Whig Party in 1835. It died off during the Civil War, having already been replaced as a major party by the Republican Party.
The article has interesting information about Americans Elect.