Forget prime time. The best battle to hit The Apprentice is taking place off screen.

Martha Stewart has spoken out on the failure of her NBC reality show, claiming the only reason her series flopped was because the Donald's version gobbled up too much airtime.

And it's a claim Trump has not taken to kindly, firing off a biting letter and bluntly saying in an interview Tuesday that his would-be successor's show "was a mistake for everybody--especially NBC."

And then it got personal.

The war of words kicked off when Stewart told Newsweek her series was intended to be the only incarnation of the show on the air and was meant to start out with her firing Trump.

"Having two Apprentices was as unfair to him as it was unfair to me," she told the magazine. "But Donald really wanted to stay on."

Apprentice producer Mark Burnett admitted that dumping the Donald was an idea they were pondering, but told the mag, "Thank God that didn't happen."

For his part, the real estate mogul turned reality-TV star initially refuted the domestic diva's version of events, simply telling the Associated Press that he was never meant to get the heave-ho.

"I wish she would be able to take responsibility for her failure," Trump said. He claimed that the only person to blame for Stewart's failure was Martha herself, saying her show didn't manage to achieve the right tone or demeanor to be a success.

But he didn't stop there.

"Your performance was terrible in that the show lacked mood, temperament and just about everything a show needs for success," he wrote. "I knew it would fail as soon as I first saw it--and your low ratings bore me out."

"Between your daughter, with her one-word statements, your letter writing and, most importantly, your totally unconvincing demeanor, it never had a chance--much as your daytime show is not exactly setting records."

And then the lowest blow of all.

"Essentially, you made this firing up just as you made up your sell order of ImClone," Trump wrote.

In a statement released late Tuesday, Stewart seemed blindsided by the vitriolic comments.

"The letter is so mean-spirited and reckless that I almost can't believe my longtime friend Donald Trump wrote it," she said. She went on to defend her ill-fated reality show and her current, Emmy-nominated chatfest.

But Trump, as always, had the last word.

The mogul appeared on CNBC's The Big Idea with Donnie Deutsch late Tuesday and expressed as much remorse as would be expected.

"Of course the letter was mean-spirited, but I think what she did was mean-spirited," Trump said of his harsh words, adding that he was upset by the claims because he was "her number-one advocate...and what does she do? She blames me for her show's failure."

Prior to the public passing of the buck over Stewart's doomed show and Trump's declining ratings, Stewart did express pleasure over her Apprentice.

"I have no regrets, whatsoever," Stewart said. "If I'd had my druthers, there would have been only one Apprentice on the air at one time. The franchise, I think, should only be one show. It shouldn't be two shows.

"I got exactly what I wanted out of it," she said. "Would I have loved it to be a runaway, giant hit? Of course. But what it was, was very good for us."

Since The Apprentice: Martha Stewart's untimely demise last December, the domestic diva has turned her sights to her other fledgling show, the syndicated Martha.

"The show is just getting smoother and better," she told Newsweek. "And I'm actually enjoying it."

Despite ratings for her daily talk show initially falling well below of expectations, it has recently shown momentum in boosting its number of viewers.

"I think that syndication will improve in the second season," Stewart said. "We'll see what happens in the fall."

In the meantime, Stewart's empire continues its global domination, with the domestic diva not only training an entire generation of housewives, but housing them, too.

Last May, Martha Stewart Living Omnimedia teamed with KB Home to build 650 mini-versions of Stewart's mansions and sell them to her admiring public.

The homes, built in Cary, North Carolina, and priced between $200,000-$450,000, were quickly snapped up, with more than 3,800 buyers wanting in.

Due to the overwhelming response, Stewart has announced plans to build at least seven more Marthavilles this week, in cities ranging from Orlando to Los Angeles.

Now that's a good thing.