Break out the cigars! Or maybe don't if grandpa is around...

Chelsea Clinton is expecting her second child with husband Marc Mezvinsky, she announced Monday on Twitter. "Next summer, Charlotte is going to be a big sister! Feeling very blessed & grateful this holiday season," she tweeted along with a photo of her 15-month-daughter.

Shortly after the big news broke, grandparents Bill and Hillary sent their well wishes to the little family. "Your dad and I could not be happier for you, Marc and Charlotte. We’re so excited to meet our second grandchild!” the Democratic hopeful tweeted, while the former President added, "Christmas comes early! Hillary and I are thrilled for Chelsea, Marc and Charlotte’s growing family in 2016!”

Clinton and Mezvinsky married in July 2010.