[Michigan Representative] Justin Amash Declares Independence from the Republican Party 

This is a link to his announcement on Facebook, because the only other official posting I've found is from The Washington Post and it's behind a paywall.

Highlights:

"George Washington was so concerned as he watched political parties take shape in America that he dedicated much of his farewell address to warning that partisanship, although “inseparable from our nature,” was the people’s “worst enemy.” He observed that it was “the interest and duty of a wise people to discourage and restrain it.”"

"The founders envisioned Congress as a deliberative body in which outcomes are discovered. We are fast approaching the point, however, where Congress exists as little more than a formality to legitimize outcomes dictated by the president, the speaker of the House and the Senate majority leader."

"Modern politics is trapped in a partisan death spiral, but there is an escape. Most Americans are not rigidly partisan and do not feel well represented by either of the two major parties. In fact, the parties have become more partisan in part because they are catering to fewer people, as Americans are rejecting party affiliation in record numbers."

"But we owe it to future generations to stand up for our constitutional republic so that Americans may continue to live free for centuries to come. Preserving liberty means telling the Republican Party and the Democratic Party that we’ll no longer let them play their partisan game at our expense."