Editor's note: This story has been updated throughout.
"I've known Glenn Hegar for many years,” Combs said in a statement released by Hegar’s campaign. “He is a man of conservative principles, strong values and great integrity. He loves his state and nation and I trust him to help lead Texas as our next Comptroller.”
Hegar is running in a Republican primary against state Rep. Harvey Hilderbran, R-Kerrville, former gubernatorial candidate Debra Medina and former state Rep. Raul Torres. Democrat Mike Collier is also running for the seat. Medina has said she may switch races and run for governor as an independent.
Though the Republican candidates have been reluctant to mention Combs on the campaign trail thus far, Hegar called her “a bold leader" Friday.
"She has helped us create an economy equal to none in the country and has worked tirelessly for the citizens of Texas," Hegar said. "I'm honored that she supports my candidacy and will faithfully carry on her legacy of transparency and government accountability if elected."
The endorsement comes two days after the conservative group Texans for Fiscal Responsibility, and its president, Michael Quinn Sullivan, endorsed Hegar over his competitors.
Hilderbran released a statement Friday morning suggesting that Combs’ endorsement will become a line of attack against Hegar in the primary.
“This election is about the future, not the past,” Hilderbran said. “The important fact is not that Susan Combs has endorsed Glenn Hegar, but that Glenn Hegar has endorsed Susan Combs' record. I respect Susan Combs for her service to the state, but her record has come up short in many areas. Part of the reason I am running is to make significant, specific improvements in the Comptroller’s office. I’ll take steps to protect taxpayers, improve customer service and implement a Texas Taxpayers' Bill of Rights. That’s why I’m running. Glenn Hegar is running to continue the status quo."
Collier said Combs' endorsement of Hegar would help voters better distinguish the candidates.
"Susan Combs missed the revenue estimate, which forced unprecedented cuts in school funding," Collier said in a statement. "She failed to protect the personal, private records of millions of Texans. Both Glenn Hegar and I are running because of Susan Combs. He's running to continue her failed status quo, and I'm running to change it."