Harvard professor Elizabeth Warren, the presumptive Democratic nominee for Senate in Massachusetts, launched a biographical TV spot today backed by a very significant advertising buy.

A Republican source told Roll Call the buy was for $770,000 over the next two weeks.

In the ad, Warren introduces herself to voters and talks about her childhood.

“I grew up in a family hanging on by our fingertips to a place in the middle class,” she says to images of old family photos. “But back then, America invested in kids like me. We had a lot of opportunities. Today, Washington lets big corporations like GE pay nothing — zero — in taxes, while kids are left drowning in debt to get an education,” Warren says directly to the camera.

“This isn’t about economics; it’s about our values,” she says. “I’m Elizabeth Warren, and I approve this message because Washington has to get its priorities straight.”

Warren faces a Tossup race against popular Sen. Scott Brown (R). Recent polls have found the contest to be very close.

“It’s a statewide buy that’s aimed at giving people a chance to learn more about Elizabeth and her priorities, especially her belief that we need to invest in our kids and help them get ahead,” Warren spokeswoman Alethea Harney wrote in an email response about the size of the ad buy.