Democratic Sen. Elizabeth Warren, who has emerged as an esteemed populist voice in Congress and a top tier campaign surrogate, says she’s been on the receiving end of sexism in the Senate.

Responding to questions about the treatment of women in the upper chamber — most recently and notably discussed by Sen. Kirsten Gillibrand — Warren told CNN's Gloria Borger that instances of gender-based discrimination aren't surprising.

"I wish it were," Warren said, taking a slight pause and sighing. "But it's hard to change these big, male dominated institutions. What I am very happy about is that there are now enough women in the United States Senate to begin to change that place and I think that's just powerfully important."

Questions regarding gender inequities in Congress gained traction earlier this summer after Gillibrand revealed several inappropriate comments by male colleagues in her new book, “Off the Sidelines.” One male senator reportedly told Gillibrand, “Good thing you’re working out, because you wouldn’t want to get porky.” Another advised her, “Don’t lose too much weight now. I like my girls chubby.”

Warren avoided going into specifics but stressed the importance of electing women to Congress. Women represent less than a quarter of all members in the House of Representatives and only 20 women currently serve in the Senate.

"Others have said it before me: if you don't have a seat at the table you're probably on the menu,” she said.

Warren -- who was in Iowa last weekend to campaign with Democratic Senate candidate Rep. Bruce Braley, and will be in New Hampshire this weekend stumping with Sen. Jeanne Shaheen -- spoke to CNN in Colorado during a swing through the state on behalf of vulnerable Democratic Sen. Mark Udall. The full interview will air Wednesday.