Click here to watch "Ringing."

Just when it looked as if Hillary Rodham Clinton would effectively cede Pennsylvania's airwaves to Barack Obama for another week, leaving surrogates to fight on her behalf, her campaign today announced the release of a new TV spot recalling the "3 a.m." ad (subscription) it ran in Texas last month.

Borrowing the imagery of that ad, which touted Clinton's readiness to be commander in chief during a national security emergency, "Ringing" (subscription) focuses instead on Clinton's economic acumen: "There's a phone ringing in the White House, and this time the crisis is economic."

"The idea is to build on an ad that was extremely successful, that people will remember and that will have resonance in the context of the 3 a.m. theme," said Clinton communications director Howard Wolfson, speaking to reporters this afternoon.

The ad's emphasis on the economy is of a piece with the campaign's larger message in the Keystone State and echoes the only other spot (subscription) Clinton has run there, as well as this week's radio buy from a pro-Clinton union.

More surprising than the ad's theme may be its focus on the Republican nominee-in-waiting. "John McCain just said the government shouldn't take any real action on the housing crisis," the narrator says. "He'd let the phone keep ringing." (Obama goes unmentioned.) The narrator then proceeds to praise Clinton's "plan to protect our homes" and "create jobs," calling her "ready" to lead -- a familiar note from a campaign that has effectively branded its candidate with the "experience" label.

When asked whether it made sense to go after McCain during a Democratic primary battle that is anything but resolved, chief strategist Mark Penn explained, "We think Democratic primary voters will rally around this spot. They will see the big difference between her and Senator McCain, and it will increase her support in the Democratic primary." He then added that the ad was "an excellent strategy during this period."