Katie Couric's Notebook: Eye On Pennsylvania

If Hillary Clinton does what polls suggest she might and easily wins today's Pennsylvania primary, she'll be like the cat with multiple lives.

Three times in this campaign, Barack Obama seemed like Mr. Momentum. By winning in New Hampshire, in California, or in Ohio, he might have pushed Clinton out of the race. And three times, the voters pulled back, and Obama failed to win.

For my full Notebook, just click the monitor.