Colleen breaks into a smile that almost touches her ears when she thinks about the moment she discovered she would become a mom. After almost a decade of trying to conceive with her husband, Randy, giving birth to her daughter felt like a “miracle.”

But following Macy’s birth, what was ostensibly the happiest time in their lives soon became one of financial and mental strain as Colleen battled postpartum depression. To make matters more difficult, her employer only provided partial paid family medical leave for 12 weeks, the amount required under New Jersey state law. The couple was forced to dip into their savings and return to work, even though Colleen was still dealing with postpartum issues and recovering from her cesarean section.

Colleen and Randy were one of the many couples on hand Tuesday for Strolling Thunder, a rally in support of federal paid family leave. Tiny tikes ran around the Capitol’s East Lawn, knocking over large building blocks and playing with striped beach balls while Speaker Nancy Pelosi and other lawmakers vowed to make paid leave a reality for millions of families.

While the rally is a play on D.C.’s annual Rolling Thunder biker ride for veterans, there were no tots on mini Harley-Davidsons to be found.

The event was sponsored by the Zero to Three campaign, a child care advocacy organization. The group is framing the policy as not just a break for tired parents, but a critical function of early childhood development. The group says parental paid time off leads to better neurological and cognitive development for newborns.

The group is also making a technocratic fiscal argument. Families, worried about rising health care costs and lack of a federal backstop, are opting to have fewer children, according to Myra Jones-Taylor, Zero to Three’s chief policy officer. In 2017, the fertility rate dipped below the level needed to replace a population, according to the National Center for Health Statistics. This creates a crisis, potentially jeopardizing Social Security, Jones-Taylor says.

The push ties in with a renewed focus on maternal health. Last month, lawmakers launched the Black Maternal Health Caucus. And Ivanka Trump, White House adviser and daughter of the president, has made paid family leave her pet issue. Jones-Taylor says she spoke to Ivanka Trump at a recent breakfast and points to her involvement as evidence of Republican support for what has traditionally been a Democratic Party issue.

Pelosi and Republican Rep. Ann Wagner said they approach the issues as grandmothers and lawmakers, concerned about the future of the country. Wagner, a member of the Suburban Caucus, said the issue would be a priority for the group. Before finishing her remarks, Pelosi thanked the audience for “strolling and being thunderous.”

Some families said they worry about having to choose between jobs and caring for a sick child.

Anna Akins’ husband walked in to find their 5-month-old son, Gareth, lying on the floor gasping for breath. After numerous trips to the hospital, he was finally diagnosed with chronic asthma, which began a trying time for the family.

Both parents are insured and have Medicaid and still had to pay out of pocket for some expenses. The 30-year-old mom is worried about how the family will pay a $14,000 hospital bill but says she and her husband agreed early on that no matter the sacrifice or financial burden from Gareth’s care, “no amount of money is worth his life.”

Stress from bill collectors hangs over the young couple’s head as they worry about building a family, saving money and providing a college education for their children. “When you can only pay $30 to $40 a month on them to try to get them paid off, it’s very stressful,” she says. “You don’t ever know who’s calling, when they’re calling and why they’re calling.”