Michele Bachmann today said fears that Donald Trump might be too biased in favor of one GOP candidate have delayed her decision to participate in an upcoming presidential debate moderated by the real-estate tycoon and reality-TV star.

"We're still in the process of looking at it," Rep. Bachmann said on CBS's "Early Show," reflecting comments the campaign has made previously to ABC News.

The Minnesota congresswoman said "one concern" about participating was an announcement Trump made that he is close to endorsing a candidate. Trump has also hinted that he might yet run as a third-party candidate against the Republican nominee.

"One concern is he's already leaning towards a candidate," she said. "So there's questions about objectivity."

Some outlets have erroneously reported that Bachmann already said she would participate; she has not.

Bachmann, who has met with Trump several times, said today, "I have great respect for him."

The debate sponsored by the conservative magazine Newsmax is slated for Dec. 27, a week before the Iowa caucuses.

Many GOP mandarins, including former George W. Bush advisers Karl Rove and Ari Fleischer, have been critical of Trump's involvement and called on the candidates not to participate.

Already, Rep. Ron Paul and former Utah Gov. Jon Huntsman have said they will not participate. Only former Speaker Newt Gingrich and former Pennsylvania Sen. Rick Santorum have signed on.