What does “triple down” in “Trump triples down on George W. Bush’s responsibility for 9/11”mean?

A Washington Post (October 18) article begins with the following passage under the headline, “Trump triples down on George W. Bush’s responsibility for 9/11.”

Donald Trump says he doesn’t flat out blame former president George W. Bush that the Sept. 11 terror attacks happened on his watch. But he can think of three reasons why one could hold Bush responsible. And, he might add, they are three things a President Trump would do very differently. “You always have to look to the person at the top,” Trump said Saturday in a telephone interview. “Do I blame George Bush? I only say that he was the president at the time, and you know, you could say the buck stops here.

I know the word, “double down” as a blackjack word, but I never heard of “triple down.”

Neither Cambridge online Dictionary nor Oxford Dictionaries carries this word.

Google Ngram shows both “double down” and “triple down” at respective 0.000.0037375 and minimal 0.000.0001722 incidence level.

What does “triple down” on somebody mean? Did Trump castigate G.W. Bush? Does it have anything to do with “three things” Trump will do if he is elected President? Is "triple down" a common word?

Solution 1:

As you indicated in your question, double doun originated from the card game. It can also mean:

To double or significantly increase a risk, investment, or other commitment

When politicians make a comment on someone or something in a seemingly wrong or politically incorrect way, they either back off by making some excuses or double down on (stick to) what they said by restating the reason why they said so.

Trump suggested that George W. Bush bears some responsibility for the 9/11 terror attacks on America and he is being criticized for the remark.

Triple down is a more exaggerated expression than double down as it more significantly increases the risk of doing so.

The author could have used "double down" in place of "tripple down", but he/she wants to emphasize it is not the first time that Trump doubled down on an issue. Next time Trump implicates someone like Bush in anything, the author might use "quadruple down".