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Hillary Clinton on Friday stepped up the ad wars with Barack Obama, releasing a 30-second TV spot that hammered away at her campaign’s theme that she will be “ready to lead from Day One” — and that the Obama campaign dismissed as fear-mongering.

The new ad shows images of children sleeping in their homes and asks viewers who they want “answering the phone” in the White House during a crisis.

The Obama campaign retaliated by re-releasing an ad in which retired Gen. Merrill “Tony” McPeak praises the Illinois senator for his judgment in opposing the Iraq war. Obama said Clinton is just trying to “scare up” votes.

“I don’t think these ads will work this time because the question’s not about picking up the phone, it is about what kind of judgment will you exercise when you pick up that phone,” Obama said in Houston Friday. “We have had a red phone moment — it was the decision to invade Iraq. Senator Clinton gave the wrong answer.”

Clinton’s new ad underscores her insistence that she has more experience than Obama. It is being launched in Texas, which holds its primary on Tuesday and where she is now trailing Obama in some polls.

The ad begins with a somber voiceover that says:

“It’s 3 a.m. and your children are safe and asleep. But there’s a phone in the White House and it’s ringing. Something’s happening in the world.

“Your vote will decide who answers that call … whether it’s someone who already knows the world’s leaders, knows the military — someone tested and ready to lead in a dangerous world.”

After panning across shots of babies and children sleeping in a quiet suburban setting, the ad cuts to Clinton answering that ringing phone.

“I will never see the threat of terrorism as a way to scare up votes because it is a threat that should rally the country around our common enemies,” Obama said in response. “That is the judgment we need at 3 a.m.”

Obama campaign manager David Plouffe noted that the ad is similar to one created for Walter Mondale during the 1984 Democratic presidential campaign. That ad, produced by Clinton adviser Roy Spence, showed a red phone in a dark room and intoned: “the most awesome, powerful responsibility in the world lies in the hand that picks up this phone.”

The ad voiceover said Mondale’s ability to know what he’s doing in a crisis was the difference between him and then-primary rival Gary Hart.

Democratic strategist Kelly Bingel said the Clinton spot even reminded her of the controversial ’60s “Daisy” ad from Lyndon B. Johnson’s campaign that showed a little girl playing a field to the backdrop of a nuclear attack.

“That’s a pretty harsh ad, but it’s a fair point for her to bring up,” Bingel said. “Clearly the Texas and Ohio votes are critical for Senator Clinton to stay in this race, and she’s taking it to the max.”

Dan Palazzolo, political science professor at the University of Richmond, said the Clinton spot taps into a clear “fear factor,” but doesn’t rise to the level of the Daisy ad.

He said it will only be effective for Clinton if she repeats the ad’s theme on the stump leading up to the March 4 vote.

“She’s gotta stick with it. She can’t just keep jumping around,” Palazzolo said. “This could be their last card that they’re playing.”

In a statement the Clinton campaign released about the ad Friday, retired Gen. Wesley Clark said: “One of the most important duties of the president is ensuring the safety of the American people. Inevitably, another national security crisis will occur. And when it does, voters shouldn’t have to wonder whether their president will be ready. As president, Hillary will be ready to act swiftly and decisively.”

Click here to see the Clinton ad.

Click here to see the re-released Obama ad.

FOX News’ Major Garrett and Judson Berger contributed to this report.