Transgender Texans, along with their families, friends and supporters, lined up for hours Friday morning to register to speak at the state legislature — demanding to be heard by the Texas Senate Affairs Committee as it gathered to consider two bills.

Senate Bill 3 and Senate Bill 91 are nearly identical pieces of legislation, both aimed at banning transgender people from using restrooms that match their gender identity in schools and other state-owned buildings in Texas. The bills specifically mandate that restrooms be used only according to the sex on a person's birth certificate, regardless of current gender.

Angie Castro, mother of a transgender child, speaks at a rally against a "bathroom bill" at the Texas Capitol in Austin, Texas, U.S., July 21, 2017. Jon Herskovitz / Reuters

A similar bill, SB 6, was passed by the Senate earlier this year but failed in the House. All three bills were introduced by Republican Senator Lois Kolkhorst.

More than 250 people signed up to speak before the Senate committee on Friday.

Brad O'Furey, government relations manager for the LGBTQ group Equality Texas, told NBC News that transgender advocates began speaking at 9 a.m., and he expected public testimony to continue late into the night.

"We hope that Sen. Kolkhorst and the Senate Affairs Committee really listen to the people that have come from across Texas to testify," O'Furey said. "There are parents, transgender children and trans adults telling stories of the harassment they've faced, the bullying and disenfranchisement — and frankly, the atmosphere that a bill like this creates."

During the public hearing for SB 6, people testified against the bill for 18 hours. O'Furey said the senate set a registration limit this time, cutting down the amount of speakers allowed to testify.

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But swarms of people arrived at the Austin rotunda early to sign up, including dad Frank Gonzalez, who counts a 7-year-old transgender daughter among his three children.

Father of trans daughter: "Stop putting the lives of Texas children on the line. Stop putting my precious child in harm's way". #txlege pic.twitter.com/ChJrXacP7Q — Chris Sgro (@cristoferosgro) July 21, 2017

Among the many speakers was Ashley Smith, the woman whose selfie with Texas Governor Greg Abbott went viral online this week after she posted it with a caption reading, "How will the Potty Police know I'm transgender if the governor doesn't?"

Besides giving direct testimony before the committee, speakers also protested the bills at a press conference in the rotunda, where Democratic Sen. Sylvia Garcia said, "I will stand with you every time, because I'm for dignity over discrimination."

Garcia called the two senate bills "bureaucratic bullying" and said they would single out already vulnerable transgender children in schools.

Sen. Kolkhorst defended the bills in an email to NBC News, stating that privacy was the issue at stake.

"Senate Bill 3 protects the privacy of Texans in restrooms and showers while also preserving Title IX advancements in women's athletics," Kolkhorst said.

The seven-member Texas Senate Affairs Committee only has two sitting Democrats; one of the Democrats voted in favor of SB 6, the earlier version of the bathroom bill. O'Furey said Equality Texas expects the latest bills — or at least one of them — to pass the committee as well.

But the bills have a range of opponents: Besides the LGBTQ community and parents of transgender kids, faith leaders spoke out at the capitol Friday alongside business leaders who warned of crippling potential losses to the state economy.

In a Tuesday interview with the Houston Chronicle, IBM Global Head of Design Phil Gilbert said legislation that targets the LGBTQ community hurts the company's ability to recruit talent.

"Because high-tech jobs can be done anywhere, companies like IBM, both large and small, have to figure out where to locate those jobs," Gilbert explained. "And those jobs have to be located places where people want to live and work."

Other Texas business leaders told the Chronicle that nationwide boycotts against North Carolina around its similar anti-transgender bill, HB 2, warned of the detrimental effects of such legislation.

But for the ACLU of Texas, the issue is a starkly legal one. Staff Attorney Kali Cohn told NBC News the bathroom bills are in violation of federal law and the U.S. Constitution.

Cohn wouldn't say whether the Texas ACLU chapter planned to sue the state, only that "since nothing has passed thus far, there’s been nothing to challenge." But Cohn did testify before the senate committee, referencing Supreme Court cases and other legal precedents the ACLU says makes SB 3 and SB 91 illegal.

"They've introduced legislation that targets transgender Texans under the guise of privacy and safety," Cohn said. "That’s not what those bills do — what they in fact do is push transgender people away from being able to participate in public life."

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