Collins is the five-term senator from Maine.
Democrats have won several key races in the high-stakes midterm elections -- with ABC News projecting that Democrats will take control of the Senate and the House.
Democratic candidate Adam Hamilton, a pastor, is projected to defeat Republican Sen. Roger Marshall and flip the Senate seat.
This the first time Kansas has elected a Democratic senator since 1932.
Democrat Rob Sand will defeat Republican Zach Lahn, flipping the seat to Democratic control for the first time in 20 years.
Sand, 44, campaigned on his record as the state auditor and built trust with voters as the only Democrat elected to statewide office. He ran on an anti-corruption platform with the slogan to help Iowa become "not redder or bluer, but better and truer."
-ABC News' Juhi Doshi and Gabrielle Vinick
Republican Texas Gov. Greg Abbott has conceded the governor's race, as ABC News projects that Democratic challenger Gina Hinojosa will win.
"I made the decision to go ahead and call Gina Hinojosa and congratulate her on winning this race for governor of the state of Texas," he told supporters in Austin.
-ABC News' Diana Paulsen
Sherrod Brown, the Ohio Democrat who was voted out of office two years ago, is projected to defeat Sen. Jon Husted, and return to the Senate.
Brown is breaking some historical trends by returning to the Senate just two years after losing his seat as only six senators have returned after losing an election since 1946.
-ABC News' Juhi Doshi
