RACHEL MADDOW (HOST): Before becoming Donald Trump's new campaign manager, Kellyanne Conway ran a Super PAC she ran one of the SuperPACs that supported Ted Cruz in the primary. You might remember in the Republican primary this year there were a whole bunch of different SuperPACs that supported Ted Cruz. They were all called some variation of Keep The Promise. She ran the group that was called Keep The Promise 1. They ran millions of dollars in anti-Donald Trump ads, incidentally, which is kind of ironic given what her job is now.

But more important than that, she ran this Keep The Promise PAC. She ran the iteration of all the Ted Cruz supporting PACs, she ran the one that was almost entirely funded by a single donor. All the money in that PAC basically came from one source. It came from New York City hedge fund billionaire Robert Mercer. He gave the money, Kellyanne Conway ran that PAC. Robert Mercer and Kellyanne Conway, they supported Ted Cruz in the primary, not Donald Trump, but once Trump won, once Cruz dropped out, that mega-donor Robert Mercer and Kellyanne Conway, they decided to switch horses, they decided to keep working together. She stayed in charge of the PAC. They changed its name. They started running anti-Clinton ads to help Trump instead of anti-Trump ads to help Cruz. But as a multi-million dollar donor to that effort -- we've talked about here on this show, Robert Mercer, this hedge fund billionaire appears to have become the single largest funder now of the effort to elect Donald Trump for president.

Robert Mercer is also reportedly the single largest funder of Breitbart.com. And so this one guy, Robert Mercer, the money man, right? He ends up being sort of the missing link. He ends up being the thing that explains, I think, in a lot of ways, why the Trump campaign is this strange thing that it is now. When the Trump campaign decided to fire the last guy in charge, Paul Manafort, and put these new folks in charge, it was an interesting and sort of inexplicable thing that they simultaneously -- they didn't fire Paul Manafort and then pick a new person to replace him. They fired Paul Manafort, but then they brought in two people. They came up with two new job titles. Campaign Manager and Campaign CEO, okay. They brought in two people at once. Kellyanne Conway, who ran Robert Mercer's Super PAC, she's a very familiar figure in Republican politics.

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But she didn't come onto the campaign alone, right? She came on as campaign manager, Donald Trump's top funder apparently installed her at the top of the Trump campaign, but he also simultaneously, on the same day, at the same time installed this other guy. This guy from Breitbart as the Campaign CEO. Robert Mercer is the money man behind both of these folks, behind Kellyanne Conway and her PAC which started as a Ted Cruz thing and then became a Donald Trump thing. Robert Mercer was the money behind that, Robert Mercer is also the money behind Breitbart.com. He funded them both to the tune of millions of dollars. He is the thing explains why those two otherwise unconnected individuals both came on at the same time, on the same day, to take over the Trump campaign.