Arizona Senator Jeff Flake announced he will not run for re-election in 2018 and gave a barnburner of a speech on the Senate floor explaining that decision.

The full transcript is here. Here are some highlights.

Let me begin by noting a somewhat obvious point that these offices that we hold are not ours to hold indefinitely. We are not here simply to mark time. Sustained incumbency is certainly not the point of seeking office. And there are times when we must risk our careers in favor of our principles.

Now is such a time.

We must never regard as “normal” the regular and casual undermining of our democratic norms and ideals. We must never meekly accept the daily sundering of our country - the personal attacks, the threats against principles, freedoms, and institutions, the flagrant disregard for truth or decency, the reckless provocations, most often for the pettiest and most personal reasons, reasons having nothing whatsoever to do with the fortunes of the people that we have all been elected to serve.

None of these appalling features of our current politics should ever be regarded as normal.

Mr. President, I rise today to say: Enough. We must dedicate ourselves to making sure that the anomalous never becomes normal. With respect and humility, I must say that we have fooled ourselves for long enough that a pivot to governing is right around the corner, a return to civility and stability right behind it. We know better than that. By now, we all know better than that.

Here, today, I stand to say that we would better serve the country and better fulfill our obligations under the constitution by adhering to our Article 1 “old normal” – Mr. Madison’s doctrine of the separation of powers. This genius innovation which affirms Madison’s status as a true visionary and for which Madison argued in Federalist 51 – held that the equal branches of our government would balance and counteract each other when necessary. “Ambition counteracts ambition,” he wrote.

If I have been critical, it not because I relish criticizing the behavior of the president of the United States. If I have been critical, it is because I believe that it is my obligation to do so, as a matter of duty and conscience. The notion that one should stay silent as the norms and values that keep America strong are undermined and as the alliances and agreements that ensure the stability of the entire world are routinely threatened by the level of thought that goes into 140 characters - the notion that one should say and do nothing in the face of such mercurial behavior is ahistoric and, I believe, profoundly misguided.

Here is Part 2:

Now, it seems that we, the architects of this visionary rules-based world order that has brought so much freedom and prosperity, are the ones most eager to abandon it.

The implications of this abandonment are profound. And the beneficiaries of this rather radical departure in the American approach to the world are the ideological enemies of our values. Despotism loves a vacuum. And our allies are now looking elsewhere for leadership. Why are they doing this? None of this is normal. And what do we as United States Senators have to say about it?

The principles that underlie our politics, the values of our founding, are too vital to our identity and to our survival to allow them to be compromised by the requirements of politics. Because politics can make us silent when we should speak, and silence can equal complicity.

I have children and grandchildren to answer to, and so, Mr. President, I will not be complicit.

Without lionizing Senator Jeff Flake, I think that this is an historic speech, and it's one which can be a turning point for Republicans. Will the dam break? Will the Republican party be split in two? Where will the neverTrumpers land?

Flake has always been a conservative -- almost fringe conservative -- and he just brought fire down on the White House, Senate leadership, and complicit Republicans.

Some gave him a standing ovation.

I would have been moved to give him one if his last line had been a call for his colleagues to impeach this president.