@chelseaclinton / Twitter 1 / 9
@chelseaclinton / Twitter 1 / 9

Double the fun! Chelsea Clinton is about to become a mommy again.

On Dec. 21, the daughter of Bill and Hillary Clinton announced on Twitter that she's expecting a second child with her husband, Marc Mezvinsky. She and Marc welcomed a daughter, Charlotte, in September 2014.

In her insanely adorable announcement, Chelsea enlisted the help of her daughter, showing her looking at a book that says "Big Sisters are the BEST."

"Next summer, Charlotte is going to be a big sister! Feeling very blessed & grateful this holiday season," Chelsea captained the image.

Ever since Charlotte's birth, Chelsea has been open about her desire to have more children.

"I didn't know I could care more intensely about anything until I became a mom. Somehow I love my husband even more, I love my parents even more. I feel even greater urgency about the work that I do, particularly around women and girls being a mom of a daughter," she told People magazine in September. "And I think my love for Charlotte has just opened more space in my heart and my brain that I didn't even know was there."

The announcement comes just a few months after she gushed about her own mom to Ellen DeGeneres, saying, "I won the mom jackpot."

"I didn't know that I could love and admire and respect my mom anymore until I became a mom and couldn't believe any more in her as the right leader for the country I want my daughter to grow up in," Chelsea said, "but I do because she has been working to ensure that every woman should get the chance to grow up to be you or to grow up and be the next Hillary Clinton."

Note to the home renovators at the White House: If Chelsea and her family get their wish, you may want to start building out a presidential nursery.