by Sean Bowditch

"It's 3am... Your children are safe and asleep... Who do you want answering the phone?"

Hmmm. Sounds familiar...

It's back! A new McCain ad uses footage from Clinton's famous "3AM" ad she rolled out during the primaries to challenge Obama's national security credentials. It also features a clip of Clinton pointing to the "lifetime of experience" McCain "will bring to the White House".

The timing of the ad is strategic: Hillary Clinton is set to deliver a much-anticipated speech tonight at the Convention in Denver. The ad seems to up the ante for Clinton. She's under increasing pressure to bring her supporters into the Obama fold and to voice a strongly unifying, Obama-focused message tonight. Will this ad provide additional motivation?

As for McCain, his strategy is not without its risks. The ad could very well win him a few votes among discontented Clinton supporters, especially women. But the link could also backfire. A new ABC News poll suggests that, among all registered voters, Clinton's favorability rating is on the decline. It's especially weak at the political center. Among independents, only 41 percent rate Clinton favorably compared with Obama's 59 percent rating.