On Sunday, Laura Bush wrote an op-ed in The Washington Post that expressed her disappointment and sadness that children were being separated from their parents at the border; on Monday, Michelle Obama backed her up on Twitter. About three hours later, Hillary Clinton tweeted that the policy is “a humanitarian crisis.” She also retweeted Bush’s op-ed. Rosalynn Carter released a statement later on Monday, against the “practice and policy” of “removing children from their parents’ care.”

Meanwhile, of the living former presidents, only Bill Clinton has tweeted directly about the crisis. On Wednesday,Barack Obama posted a lengthy Facebook message in honor of World Refugee Day that referred obliquely to “ripping children from their parents’ arms.” There is power in these actions and lack thereof; when Americans are looking for change from their leaders, they have often found it instead in those leaders’ wives.

Throughout history, First Ladies have been charged with traditional “female” roles, from planning the menu at state dinners to decorating the White House at Christmas. When they’re in the White House, First Ladies often focus their efforts around broadly supported, family-friendly issues, like literacy or nutrition. Their comments about family separation at the border, though pointedly political, also fit with a First Lady’s traditional focus on family issues.

But they also have a long tradition of being more outspoken than their husbands on key issues, even when they occupy the same White House. In 1776, more than a decade before she would become First Lady, Abigail Adams urged her husband and his fellow members of the Continental Congress to “remember the ladies.” Eleanor Roosevelt supported an anti-lynching bill that her husband was resisting. Barbara Bush visited babies with AIDS in 1989, her first year in the White House. Michelle Obama used her 2016 Democratic National Convention speech to popularize the phrase “When they go low, we go high” in reference to Donald Trump. Hillary Clinton used a 1995 speech in Beijing to declare that “women’s rights are human rights.”

Without ever running for office or holding an official political position, First Ladies become among the most visible people in the country, wielding a soft power that often makes them more popular than their husbands. In 1985, Nancy Reagan reached an approval rating of 71 percent, which still topped her husband’s highest rating of 67 percent. It’s worked for Melania Trump, too; a CNN poll in May found that 57 percent of Americans approve of Melania, compared to her husband’s 43 percent.

It would be easy for these First Ladies to maintain their popularity by staying quiet on the issues that matter, but again and again, these women have found their moments to speak out. Even Hillary Clinton, one of the most anomalous of former First Ladies who learned to speak carefully as a politician, has found her voice in her post-political life. Last spring, Clinton declared she had “joined the resistance” against Trump.

Former presidents are often known to develop tight bonds when they’re outside the office; Bill Clinton and George W. Bush have a continuously blossoming friendship. Herbert Hoover and Harry S. Truman developed a friendship over helping World War II refugees. First ladies have done the same; last year, Laura Bush and Hillary Clinton both championed a National Women’s History Museum, something that has been a long effort in the making at the Women Making History Awards gala. Hillary paid tribute to Laura as she was being honored at the event: “I thank her for her example and her leadership,” Clinton said of her fellow former First Lady.

In 2013, Laura Bush and Michelle Obama joined forces on the stage in Tanzania at an African First Ladies summit. Their husbands were also in the country, reportedly making it the first time two U.S. presidents had been in an African country at the same time. “They’re learning from us,” Michelle joked to Laura onstage. Though their husband’s policies and parties differ, the women spoke about the similarities driving them together.

“We all know what it is like to have your husband be president,” Laura said at the summit. “We First Ladies have a lot of things we can talk about together that no one else really will understand.”

This article has been updated to include a statement by Barack Obama.