Top Republican senator Bob Corker will retire before the 2018 election

Top Republican Sen. Bob Corker will not seek reelection in 2018, he announced on Tuesday.

"I have always been drawn to the citizen legislator model, and while I realize it is not for everyone, I believe with the kind of service I provide, it is the right one for me," Corker said.

He continued: "I am grateful to the people of Tennessee for the opportunity to serve my state and my country."

The chair of the Senate Foreign Relations committee has been weighing his decision for months, with top Republicans like Senate Majority Leader Mitch McConnell urging him to seek reelection, despite some earlier polls indicating he may be vulnerable to a Republican challenger in a primary.

Indeed, some on the right have amped up their search for a candidate to run to Corker's right, particularly following the Tennessee senator's criticism of President Donald Trump's comments about white nationalist protesters in Charlottesville, Virginia.

Former White House chief strategist Steve Bannon has reportedly sought a primary challenger to Corker.

Though Tennessee is considered a Republican stronghold, the open seat could also present an opportunity for a Democratic upset in a wave election year.