Rob Portman Says No To 2016 Presidential Race

— -- It’s not even 2015, and the 2016 presidential race already has its first dropout.

Ohio Sen. Rob Portman, a Republican who was once considered a top contender to be Mitt Romney’s vice presidential nominee in 2012, said in a statement early Tuesday morning that he would not seek the 2016 Republican presidential nomination. Instead, he said, “I have decided to run for re-election in 2016. I am excited about continuing to serve, especially with the change in the Senate leadership.”

“With the new Republican majority, I see a real opportunity over the next two years to break the gridlock in Washington and actually get things done to help Ohioans and all Americans. That's where I believe I can play the most constructive role,” he said. “I don't think I can run for president and be an effective senator at the same time.”

In an interview with ABC News' Jonathan Karl earlier this fall, Portman said he was "taking a look" at a White House bid in 2016.

"I am concerned about the country, and I want to see who else jumps in,” the Ohio Republican told ABC News. “I think it's a pivotal election so I am concerned enough that I am taking a look at it.”

In 2013, Portman, a former budget director in President George W. Bush's administration, became the lone GOP senator at the time to support same-sex marriage when he revealed he made the decision because his son, Will, is gay.

For now, Portman said, "I'm excited to roll up my sleeves to make a difference for the people of Ohio and the country. While I appreciate the encouragement I have received from many to run for president, my focus will remain on Ohio and running for re-election to the Senate in 2016. I look forward to formally announcing my re-election campaign in the new year."