In a political season that's seen candidates' spouses play unprecedented roles, Sen. Barack Obama called for a new standard Monday that seeks to redraw the battle lines of the general election: Keep the spouses out of it.
"If they think that they're going to try to make Michelle an issue in this campaign, they should be careful because that I find unacceptable," Obama said on ABC's "Good Morning America." "For them to try to distort or to play snippets of her remarks in ways that are unflattering to her, I think is just low class."
"These folks should lay off my wife. All right? Just in case they're watching," he said with a wry smile.
But Obama's plea for a spousal cease-fire appears unlikely to result in any major changes in the tenor of the campaign.
The Democratic National Committee has aggressively targeted Cindy McCain over her decision not to release her tax returns, and DNC officials said Monday that they would continue to do so, saying the issue raises questions of "transparency and credibility."
Former President Bill Clinton has been a tireless campaigner on behalf of his wife, Sen. Hillary Clinton, and a series of comments he's made about her campaign against Obama became immediate campaign fodder.
And -- in what prompted Obama's warning -- Republican groups and state party organizations have already begun to use some of Michelle Obama's comments in advertisements and fundraising appeals as they seek to make a broad case against her husband's candidacy.
Even if candidates could agree not to mention one another's spouses, outside groups cannot be controlled. And the growing role played by political spouses in general makes requests like Obama's impossible to fulfill.
"It's not possible to put it off-limits," said Jeffrey Berry, a political science professor at Tufts University. "If Michelle Obama is making political statements, she's fair game, and she has been doing that. Overall, she's been a plus, but she's vulnerable when she says things she shouldn't, just like everybody else."
'Proud' Remarks & Taxes
Obama's comments about his wife come after an effort by the Tennessee Republican Party to attack Michelle Obama over comments she made on the campaign trail earlier this year.
In February, referring to the sense of excitement among Democrats over her husband's candidacy, Michelle Obama said, "For the first time in my adult life, I am proud of my country."
Said the state GOP: "The Tennessee Republican Party has always been proud of America."
Obama's warning to his wife's critics drew a harsh response from the McCain campaign, with aides pointing out that the DNC has repeatedly blasted Cindy McCain for not releasing her tax returns.
"I think Obama should get his party under control before he starts issuing edicts," said Jill Hazelbaker, a McCain spokeswoman. "Instead of attacking John McCain today, maybe Obama ought to spend the day talking to Howard Dean about what is appropriate in this campaign."
DNC officials call that a dodge: Cindy McCain's tax returns have a direct bearing on potential conflicts of interest that could affect her husband's judgment, they say. Cindy McCain runs her family's beer distributorship, and her personal wealth is estimated at more than $100 million.
"Is the McCain campaign suggesting that transparency is not a relevant issue in this campaign?" said Karen Finney, a DNC spokeswoman. "The McCain campaign knows very well that releasing the tax records are an issue of transparency and credibility. Suggesting anything else is an obvious attempt to distract from the issue."
Mrs. Obama's Role Expands
Michelle Obama has played a growing role in her husband's campaign in recent months.
Early in the campaign, she was put into action mainly to headline fundraisers and to campaign among largely African-American crowds in places including South Carolina and Washington, D.C.
In the heat of the voting season, she's typically been on the trail a few days a week, with more events scheduled on the eve of primaries. Last month, she appeared on Stephen Colbert's Comedy Central program -- where she gamely parried Colbert's mock advances.
Like Bill Clinton -- though unlike Cindy McCain -- she generally campaigns by herself, drawing decent-size crowds and offering her own version of her husband's argument. She quotes her husband in calling herself "the cynic in the family," and seeks to relate her working-class upbringing to diverse audiences.
"I'm behind this man because I'm curious to see what happens when you get someone who's decent and smart and honest and connected and what happens when you engage a democracy around that leadership," she said at a campaign event in Indianapolis last month.
"You know, how do you effect change? And we've been pleasantly surprised, but there's a lot of work to do because this whole process works against everything that Barack is trying to do -- and it's been interesting to watch, but we're hopeful."
Cindy McCain has been far less vocal on the campaign trail, though she recently sat in as a co-host on "The View."
Notably, she stepped up to the microphone at an event with her husband in February, to respond to Michelle Obama's "proud" comment.
"I just wanted to make the statement that I have and always will be proud of my country," she said.