What did Hillary Clinton know about former aide Sidney Blumenthal's toxic anti-Obama innuendoes and when did she know it? That question emerged from a day of back-and-forth between the Republican and Democratic nominees for president Friday.

GOP nominee Donald Trump is known to have helped spread the conspiracy theory known as birtherism. Birthers alleged that President Barack Obama, among other things, was not born in America and did not qualify as a "natural born citizen" for the purposes of serving as president.

Trump's hounding of Obama on the issue finally prompted the president to retrieve and release his birth certificate in 2012, proving that he was indeed born in Hawaii.

However, in his final repudiation of birtherism Friday, Trump added a twist. He alleged that "Hillary Clinton and her campaign of 2008" had in fact "started the birther controversy."

The Clinton campaign and professional fact checkers promptly called Pinocchio on Trump on this issue. Yet new details emerged Friday night that cast the 2008 Clinton campaign in a highly unfavorable light, to say the very least.

One of Clinton's senior advisors on that campaign was Blumenthal. Clinton had wanted to take him with her to the State Department the next year when Obama nominated his old rival to serve as secretary of state. She was largely allowed to get her way on personnel decisions, but not this time. White House chief of staff, and current Chicago mayor, Rahm Emanuel, personally put the kibosh to that.

The New York Times reported in 2009, "Secretary of State Hillary Rodham Clinton wanted to hire Mr. Blumenthal, a loyal confidant who had helped her promote the idea of a 'vast right-wing conspiracy' more than a decade ago. But President Obama's campaign veterans still blamed him for spreading harsh attacks against their candidate in the primary showdown with Mrs. Clinton last year."

It now looks like those "harsh attacks" that Blumenthal spread included birtherism. James Asher, former editor of McClatchy's DC bureau alleged Friday that Blumenthal had in fact directly brought the allegations to the newspaper chain in 2008 and asked them to investigate.

Blumenthal denied that he'd spread the rumor in an email to the Boston Globe. But later in the day, McClatchy itself made it clear that the charge has merit. In fact the chain sent a reporter to Kenya at Blumenthal's urging, to look into what he had to say "and that reporter determined that the allegation was false."

What Clinton knew of Blumenthal's attempted dirty tricks is an open question. But after the Obama administration shot down his appointment to the State Department, the Clintons then employed him at the Clinton Foundation and his regular correspondence with Madame Secretary features prominently in many of her now public, non-deleted emails.

The two were very closely linked for some time, in other words. If Blumenthal now has a birther problem, then Clinton has one too at a time when she ought to have other things on her mind.