"He's got a right to comment on our military policy because he's served our country with valor," Clinton told the audience.
A state representative from Houston, Noriega also is an Army National Guard lieutenant colonel who patrolled the U.S.-Mexico border and trained Afghani troops. Recently, Noriega got the endorsement of the political action committee for the Veterans of Foreign Wars, a national organization of about 2.2 million members.
"We need a senator that's ready to fight to bring my brothers and sisters home," Noriega said.
Cornyn is a member of the Senate Committee on Armed Services.
Taking on Cornyn hasn't been easy on Noriega. Cornyn has raised and spent more money than Noriega and even made some headway in the typically Democratic Rio Grande Valley.
But Clinton told a cheering crowd in which many waved red, white and blue signs reading "Rick Noriega for U.S. Senate" that this campaign season taught him a candidate can be outspent and still win.
The former president's wife, Sen. Hillary Rodham Clinton, campaigned earlier this month for Noriega in South Texas.
Noriega is expected to carry the Rio Grande Valley, a region dominated by Hispanics and veterans.
But he's had little advertising, dashing some of the potential for building more name recognition for himself.
Noriega recently launched his first television ad of the general election season. Titled "Fed Up," it has Noriega saying families have lost their homes and their savings and that it's time for a new kind of senator.
"What's wrong with peace, prosperity and a balanced budget," Noriega asked the Dallas crowd.
Slideshow archive | ABC13 wireless | Help solve crimes