Kirsten Gillibrand — a better bet than Hillary?

Let's assume for the moment that becoming the next U.S. president is just not in the cards for Hillary Clinton. Who would you put your money on to become America's first female commander in chief? An outspoken progressive like Elizabeth Warren? A former CEO like the recently declared Carly Fiorina? And then there's one other woman, one with a resume similar to Clinton's — Democrat, lawyer, senator from New York — but without the appended baggage: Kirsten Gillibrand.

In roughly a decade in Congress, Gillibrand, 48, has blazed a path...