In a lightning response, Obama parodied her ad with one of his own - the same ominously ringing phone, the sleeping children, the mood lighting, even the same introduction: "It's 3 a.m. and your children are safe and asleep."
The Obama ad intones: "In a dangerous world, it's judgment that matters."
His point: When Clinton had her "red phone moment," as he put it in a speech earlier in the day, she helped send the U.S. into Iraq, while he stood against the war from the start.
Clinton's foreboding ad, shown in Texas, prompted an immediate denunciation from Obama, who said it's meant to scare people.
Clinton later told a rally, "I don't think Texans scare very easily.
"We have never had a presidential campaign where national security wasn't an issue and we're not about to start now," she told more than 500 people. She was flanked by former top military leaders backing her campaign, including retired Army Gen. Wesley Clark.
Obama rolled out testimonials from his own national security supporters that the Illinois senator has the temperament and judgment for perilous times.
The commercials stirred waters heading into the final weekend of the campaign for Ohio and Texas presidential primaries Tuesday that could make or break Clinton's campaign.
The Clinton ad evoked comparisons to Lyndon Johnson's infamous "Daisy ad" against Barry Goldwater in 1964 - the safety of children in a crisis - but without the mushroom cloud image and alarmist words that prompted that ad to be pulled after one showing, and talked about ever since.
Clinton, a second-term New York senator and former first lady, is casting herself as the candidate with the years of service needed to take command on Inauguration Day.
Obama, a first-term senator, is seeking to chip away at those arguments by suggesting he would have superior judgment.
His Exhibit A: He opposed the Iraq war before it started, while she voted for it, and now wishes she could take that vote back.
To the sound of a ringing phone, the Clinton ad shows children sleeping at night and a mother checking on a child as an announcer says a phone is ringing in the White House and something has happened in the world.
"Your vote will decide who answers that call," the voice says.
"Whether it's someone who already knows the world's leaders, knows the military - someone tested and ready to lead in a dangerous world."
It ends with an image of Clinton on the telephone as the announcer reprises the line, "It's 3 a.m. and your children are safe and asleep," and adds: Who do you want answering the phone?"
Obama responded that he called it right on the war, "the most important foreign policy decision of our generation, and that's the kind of judgment I'll show when I answer that phone in the White House as president of the United States."
"We've had a red phone moment," he added. "It was the decision to invade Iraq. And Senator Clinton gave the wrong answer."
Clinton spokesman Howard Wolfson disputed that the Clinton ad was similar to what he misidentified as the "dandelion ad" of 1964. He called the Clinton ad soft and positive.
In the daisy ad, a young girl counts up the petals she plucks from a daisy but stops as a voice-over begins the countdown for a missile launch, then she looks up into a sky engulfed in the firestorm and mushroom cloud of a nuclear blast. Johnson's voice comes on and says: "These are the stakes, to make a world in which all God's children can live or go into the darkness. Either we must love each other or we must die."
In portraying Johnson as the leader who would keep children safe, the ad did not mention Goldwater, while underscoring fears he was a warmonger. Goldwater complained and the ad was pulled.
The Clinton ad resembles one in 1984 from the Democratic primaries - with the children added.
A Walter Mondale commercial that year simply showed a red crisis phone and said: "The most awesome, powerful responsibility in the world lies in the hand that picks up this phone. The idea of an unsure, unsteady, untested hand is something to really think about."
The ad concluded: "This president will know what he's doing, and that's the difference between Gary Hart and Walter Mondale."
Underscoring Obama's argument was an endorsement Friday from Sen. Jay Rockefeller, D-W.Va., the chairman of the Senate Intelligence Committee and a superdelegate with a vote at the party's nominating convention this summer.
"Barack Obama is the most qualified person - Democrat or Republican - to lead our country in the face of enormous challenges, the very real threat of terrorism, economic uncertainty, and instability at home and abroad," Rockefeller said in a statement.
The Obama campaign also responded to the new Clinton spot by rebroadcasting an ad in which retired Gen. Merrill McPeak, the Air Force chief of staff from 1990 to 1994, endorses Obama.
Then came the ad about Obama at 3 a.m. "When that call gets answered, shouldn't the president be the one - the only one - who had judgment and courage to oppose the Iraq war from the start? Who understood the real threat to America was al-Qaida in Afghanistan, not Iraq?"
