Austin: A Democratic awakening in Texas stopped shy of putting Beto O'Rourke in the US Senate, but in Houston one major upset prevailed: a 27-year-old Colombian immigrant, who has no political experience, was elected as the top official of the nation's third-largest county.

Democrat Lina Hidalgo came to the US as a teenager in 2005, just two years before popular Republican Harris County Judge Ed Emmett took office and later steered Houston through some of the nation's biggest natural disasters.

Immigrant Lina Hidalgo will lead the third largest county in the US. Credit:Twitter

Now Hidalgo has his job after ousting him in a historic and narrow victory on Tuesday night that was largely unexpected, but also a clear signal of Democrats having new life in Texas after decades of lopsided defeats and little political power outside big urban cities.

"Easily the most under appreciated upset in Texas," tweeted Julian Castro, former President Barack Obama's housing secretary, who is leaning toward making his own presidential run in 2020.