(WATCH) Moms for Liberty

Across the nation, parents are pushing to wrest control from school systems that they claim are overreaching, whether it's advancing a transgender agenda or pressing critical race theory that some allege to be racist. Two Florida moms who started a grassroots movement have seen their star rise. Lisa Fletcher catches up with them on the national stage in Philadelphia.

The following is a transcript of a report from "Full Measure with Sharyl Attkisson." Watch the video by clicking the link at the end of the page.

The solidly Democrat city of Philadelphia might not seem the best place for conservatives to choose for a meeting.

But for the group "Moms for Liberty," the birthplace of American democracy is an ideal location, fitting their mission of helping parents defend their rights.

On the left is Tiffany Justice and her friend Tina Descovich. They started Moms for Liberty just three and a half years ago.

When we first met them, the organization was still relatively small, operating out of a newly-rented office in central Florida. Then the two former school board members talked about why they got started.

Tiffany Justice: We're about parental rights. Every parent has the fundamental right to direct the upbringing of their children, their medical care, their healthcare, their education.

That's a message that took hold as Covid restrictions swept the nation. Chapters of the group soon formed in dozens of states, members attending school board meetings to express their frustration and anger.

Fast forward to this summer, as members gathered in Philly for their convention. It was clear how powerful they’d become as a succession of Republican candidates came to meet them.

Ron DeSantis: And I think what we've seen across this country in recent years has awakened the most powerful political force in this country: mama bears.

Even the man leading the race was there to try and win their support.

Donald Trump: In school board races, PTA meetings, and town halls across the nation, you have taught the radical left, Marxists, and communists a lesson they will never forget: don’t mess with America’s moms.

Their group’s star power has meant the founders are new stars of the conservative movement.

Justice: If someone is demonstrably harming our children, we are going to come together to fight to protect them.

Tina Descovich: We are in a fight for liberty. We are in a fight for the future of this country. It doesn’t look like the fight 250 years ago, but make no mistake: this is a fight. America needs you right now. America needs courageous people.

Lisa: Wow. Did you guys ever expect it was going to get this big, this fast?

Justice: I did. We don't have any time to waste, and our children are struggling in schools, and we're watching that happen. And every year that a child continues to either be locked out of a school, right, or to be indoctrinated in schools, it's a stolen year from them, and it has to stop.

Descovich: We've had a lot of successes this past year in Florida and South Carolina. Ten or 15 states around the country with Parental Bill of Rights, transparency bills in education. So it's still very local, but they're working to impact at all levels of government.

But right from the beginning, Moms for Liberty has been a target for those on the political left. Opponents have accused individual members of bad conduct and hateful speech.

A North Carolina chapter reportedly showed up at a school board meeting with members of the white nationalist Proud Boys. In Indiana, a chapter used a quote from Adolf Hitler in its newsletter, for which they later apologized. And several members have been accused of harassment, including one in Pennsylvania, fined $200 for multiple harassing Facebook messages. One of the most consistent criticisms is that Moms for Liberty wants to ban books.

Justice: Curating the content of a children's library is not banning books. You wouldn't have the same books in a medical college that you would in a seminary.

On the streets outside the groups' meeting, we found a small but loud gathering of protestors.

Woman: We're here to protest Moms for Liberty. We have 18 active chapters in North Carolina. We know that they're spreading their hate and their propaganda and their bigotry across the country. There were threats to our public schools.

Lisa: The Southern Poverty Law Center recently branded Moms for Liberty a hate group. The Southern Poverty Law Center — their judgments are not without controversy. But what they said is that you're extremists, that you're advancing an anti-student inclusion agenda, and they said that you're seeking to undermine public education holistically and to divide communities. Are you extremists?

Descovich: This is nonsense. It's absolute nonsense. They titled us, they put us under the subhead of anti-government extremist group. My answer to that is we endorsed in 500 school board races last year. We won 275 school board seats last year. We are taking part in our government. We are going through the process exactly how we were meant to go through the process to advocate our values and our vision of what we want to see for America.

Moms for Liberty say they are often the ones facing harassment, pointing to their Twitter account being shut down and Facebook blocked. For a time, PayPal froze their assets, and their opposition petitioned the Marriott to cancel their convention.

When Justice appeared before Congress earlier this year, it was to directly accuse the Biden Justice Department of targeting parents who speak out at school board meetings.

Justice: One minute, you're making peanut butter and jelly, and the next minute the FBI is calling you. You answer the phone, and they want to talk to you about your comments at a school board meeting last week. Do you have any guns in your home? Do you have a history of mental health illness? Oh, and by the way, don’t tell anyone we called.

Perhaps the biggest sign that Moms for Liberty are now at the center of the political debate: the 131 media outlets that covered their convention.

Lisa: Where does this go from here?

Justice: Continuing to grow, more chapters, more joyful warriors standing up and telling the truth all over the country.

Descovich: We know who we are. Our moms in that room right now, they know who they are. You can call them all the names in the world; they will not stop fighting for their children and for the future of this country.

And despite leading a conservative national movement, Descovich and Justice say they’re too busy to consider running for office themselves.

For Full Measure, I'm Lisa Fletcher in Philadelphia.

Watch story here.