Pennsylvania's Six Week Primary Ends Tonight

April 22, 2008 — -- For the last six weeks Sens. Hillary Clinton, D-N.Y., and Barack Obama, D-Ill., have battled and bickered and both have unleashed a barrage of negativity in television ads that have aired thousands of times in the state.

That barrage of ads will come to an end today as the Democrats of Pennsylvania head to the polls in what could be a make-or-break day for Clinton, or prolong the Democratic primary season into at least another month.

In an ad that began airing in Pennsylvania Monday morning, Clinton implies she is tougher than Obama.

"Who do you think has what it takes?" the narrator asks in an ad depicting historical images of crises that presidents have had to deal with: Osama bin Laden, headlines about the stock market crash of 1929, long gas lines from the 1970s oil-shocks, images of the Cold War, Hurricane Katrina and soldiers. It features the first image of Osama bin Laden to be used in a TV ad this political season.

"It's the toughest job in the world," says the ad's narrator. "You need to be ready for anything — especially now, with two wars, oil prices skyrocketing and an economy in crisis."

The ad quotes President Harry Truman's famous line: "If you can't stand the heat, get out of the kitchen," — to cast Obama as complaining about last week's ABC News presidential debate.

Responding to the ad, Obama spokesman Bill Burton accused the New York senator of engaging in scare tactics.

Clinton further displayed tough talk in an interview airing on "Good Morning America" Tuesday. ABC News' Chris Cuomo asked Clinton what she would do if Iran attacked Israel with nuclear weapons.

"I want the Iranians to know that if I'm the president, we will attack Iran," Clinton said. "In the next 10 years, during which they might foolishly consider launching an attack on Israel, we would be able to totally obliterate them."

Watch the full interview with Sen. Hillary Clinton on "GMA" Tuesday.

Obama, for his part, has to be worried about obliterating his repeated promise of a "new kind of politics." But he told ABC News' Robin Roberts on "Good Morning America" his attacks are necessary.

"You've always got to measure if somebody throws an elbow at you, and after three or four times of gettin' elbows in the ribs, you know, at what point do you sort of say, 'OK, you know, we, we, we've gotta put a stop to that'?" Obama said.