Updated

Tennessee Sen. Bob Corker is apparently having no more second thoughts about leaving Congress at the end of the year.

A top aide to the Republican said Tuesday that Corker considered jumping back into the race for the seat but has decided against reversing that decision.

"Over the past several months, Senator Corker has been encouraged by people across Tennessee and in the Senate to reconsider his decision not to seek re-election,” Todd Womack, Corker’s chief of staff, said in a statement. “Based on the outpouring of support, we spent the last few days doing our due diligence and a clear path for re-election was laid out.”

“However, at the end of the day, the senator believes he made the right decision in September and will be leaving the Senate when his term expires at the end of 2018,” Womack said.

Tennessee GOP Rep. Marsha Blackburn, who is running for the seat and would have run against Corker had he reversed his decision, reacted by calling on Republicans to unite behind her.

"I want to thank Senator Corker for his dedicated service on behalf of Tennessee families. Now, we can unify the Republican party and focus on defeating Democrat Phil Bredesen in November,” Blackburn said.

CORKER 'LISTENING' TO THOSE URGING HIM TO RETHINK RETIREMENT

Corker recently had conversations with the White House and his Republican colleagues in the Senate about the possibility of reversing his decision to retire amid concerns from some Republicans that Democrats would have a decent shot at flipping the seat.

One recent poll, conducted by Republican pollster Glen Bolger and obtained by Fox News, showed Democrat Phil Bredesen with 47 percent to Blackburn’s 45 percent in a hypothetical matchup. The GOP currently holds a slim 51-49 majority in the Senate.

Others made the argument to Corker, the chairman of the Senate Foreign Relations Committee, that his foreign policy knowledge is critical, with Arizona Republican Sen. John McCain in poor health and House Foreign Affairs Chairman Ed Royce, a Virginia Republican, retiring this year.

The Blackburn campaign strongly pushed back against those arguments, with spokesman Andrea Bozek recently telling Fox News, “Anyone who thinks Marsha Blackburn can’t win a general election is just a plain sexist pig.”

Fox News’ Jason Donner, Ross Lee and Mike Emanuel contributed to this report.