ABC News' Michael Falcone reports:

DES MOINES - Another one bites the dust.

Michele Bachmann has officially said "no" to the Donald Trump-moderated Newsmax debate scheduled for later this month.

"We have confirmed that we are not participating," Bachmann spokeswoman Alice Stewart told ABC News on Thursday.

Bachmann has been especially aggressive in her courting of the real estate and reality television mogul, paying several personal visits to Trump Tower over the past few months in search of an endorsement.

So, this leaves just two candidates - Newt Gingrich and Rick Santorum - who plan to show up at the Dec. 27 event in Des Moines.

Mitt Romney, Jon Huntsman, Rick Perry, Ron Paul have all declined to attend. Perry became the latest to decline Trump's invitation on Thursday.

The Perry campaign communication director, Ray Sullivan, said "traditional retail campaigning" was the Texas governor's "top priority" in the closing weeks before the first nominating contests.

Bachmann's spokeswoman declined to elaborate on why the Minnesota congresswoman decided not to attend.