AUSTIN – Leaving home and venturing out in public creates anxiety for Brenden Kaplan, 16.

He was born a girl but transitioned to a boy several years ago.

Brenden, who lives in Grapevine, said he will not drink any fluids for an hour before going out in public because of fear of having to use a public restroom.

“If my family is out and we’re having a good time and I have to go to the bathroom, we have to go home because I don’t feel safe in public,” he explained.

Brenden, who has already gone to court to get his sex changed on his U.S. Passport and his identification, is now homeschooled because of bullying from classmates.

He worries what will happen if Senate Bill 6, better known as the bathroom bill, becomes law.

Among other things, the legislation would require people to use the public restroom they were born with.

On Monday transgender students, including Brenden, their parents, businesses, tourism associations including Dallas’ Convention and Visitors Bureau, and the South by Southwest Festival, all rallied against the bill.

“We want them to know we’re here,” said Angela Castro, a mother from Mansfield.

She is here with her daughter Roxy who attends public school.

“I am 13 and I was born biologically male and I think I started transitioning early – it was really early. I think it was fifth grade,” said Roxy. “They give me a private bathroom. But sometimes I’ll have to walk across school just to get to a bathroom.”

Hundreds are expected to fill the Capitol tomorrow for the first fight over SB6.

The Senate’s State Affairs Committee will hear testimony on the bill beginning at 8 a.m. on Tuesday.

Supporters of SB6 argue it's a privacy issue and is needed to protect women and children from predators. The bill makes reasonable accommodation for transgender people, they point out.

Supporters even launched “Operation one million voices” in hopes of getting a million Texans to back the bill.

But opponents call the legislation a solution in search of a problem, and add that existing laws already cover predators going into women’s restrooms.

Despite State Senator Eddie Lucio, D-Brownsville, switching sides and backing the bill, Lt. Gov. Dan Patrick is said to be a couple votes short of the 19 needed to bring a bill to the floor.

Patrick said he's confident that the legislation would eventually be passed out of the Senate.

State Senator Konni Burton had expressed concern over SB6, but her office told WFAA on Monday that she would support it after an amendment is introduced on Tuesday.

Despite opposition, this legislation is likely to sail through the Senate.

But it’s future from there remains uncertain. Neither the speaker of the house nor the governor have given it any vocal support.

“The House does what the House does. The governor speaks for himself. But the governor has been on the record supporting other issues like this,” explained Lt. Gov. Dan Patrick, R-Texas.

North Carolina’s lieutenant governor, who will testify on Tuesday, debunked reports of a business backlash there after his state passed something similar.

“That most extreme impact equates to one tenth of one percent of our annual GDP. That’s the economic impact; one tenth of one percent of our annual GDP. No businesses left North Carolina,” said Forest.

Still, it’s a risk that opponents don’t want Texas to take.