(John Moore/Getty Images)

Bush, who some may recall was president from 2001 to 2009, had been He Whose Name Shall Not Be Uttered for months, languishing in utter obscurity. He was invisible during the GOP primaries and through the Republican convention, which he didn’t attend (was there a scheduling conflict?).

Romney’s running mate, Rep. Paul Ryan, has even sharply criticized the Bush administration’s spending. And when Bush visited Romney’s Boston headquarters — Romney was in Nevada — the Romney campaign initially denied that he had been there.

During the first debate, Bush’s name came up but once. (Some observers assumed that was only because President Obama essentially had forgotten to show up for that debate.) In contrast, former President Ronald Reagan, who left office 24 years ago, came up three times in that face-off.

This time, the candidates invoked the 43rd prez a full 12 times by our quick count.

The bipartisan pact of not mentioning old whatsisname would have remained intact were it not for audience member Susan Katz, who actually remembered Bush and forced former governor Mitt Romney to contrast his views with those of the former president.

Romney, who has shown extraordinary skill in pivoting from an “extreme conservative” in the primaries to the proud moderate ex-governor of Massachusetts, also had momentarily forgotten Bush 43.

But he did come up with a response, saying “President Bush and I are — are different people, and these are different times,” and noting that Bush didn’t “crack down on China” and didn’t do much for small business.

Video: Gov. Mitt Romney responds to a question about what makes him different from former President Bush during a debate with President Obama at Hofstra University in New York.

Obama shockingly violated the “no-mention” agreement to paint Romney as more “extreme” than Bush on immigration, Planned Parenthood and Medicare as a voucher.

Unclear if Bush can sustain his comeback into the third debate.