HOUSTON Lina Hidalgo, chief executive of the third-largest U.S. county and the largest one in Texas, has checked in to a medical facility outside the state to be treated for clinical depression, she said on Monday.

Hidalgo, a Democrat elected in 2018 to lead the county of 4.9 million residents, has battled Republican state officials over election administration and police funding. Last November, she won re-election as Harris County judge against a well-funded political novice with a slim margin of about 17,000 votes.

Hidalgo has also clashed with county's district attorney, Kim Ogg, and in June cursed during a public commissioners' meeting in a discussion related to Ogg.

Three of Hidalgo's former aides have been indicted for helping steer COVID-outreach contracts to a party consultant.

"I am one of the over 21 million American adults that is suffering from clinical depression," Hidalgo said in a public letter, adding she was diagnosed and entered a treatment facility last month. She hopes to resume a normal schedule by early September, Hidalgo wrote.

(Reporting by Gary McWilliams in Houston; Editing by Matthew Lewis)