The above video is from August, proof that this has been at least a few months coming.

Business Insider and frequent MSNBC panelist Josh Barro announced Sunday that he is switching parties and becoming a Democrat. The reason is largely Donald Trump.

And the timing of it is based on New York's party change deadline:

In the accompanying article, Barro points out that he's always been a Massachusetts Republican in the mold of Bill Weld and Mitt Romney, and has never supported Donald Trump. And he lays the blame for Trump and the current state of the party right at the feet of Marco Rubio, Ted Cruz, and most of all Paul Ryan, for their cowardly "support but not endorse" stand regarding the orange menace:

...they know exactly what they are doing: They are taking an action that risks the destruction of the American republic to advance their personal interests.

They know what [Meg] Whitman knows about the risks Trump poses to America. Rubio himself warned specifically of the risk of Trump starting a nuclear war! But they do not care.

I can conclude from the available evidence only that they love their careers more than they love America. And they are why I quit the Republican Party this week.

He also sees no reason to be an independent. He doesn't need to agree with everything the Democratic Party does in order to use party structure to accomplish goals.

Welcome to the Party, Josh. It's a nice big tent full of relatively sane people. And you're welcome.