Rep. John Tanner (D-Tenn.), a leader of the Blue Dog Coalition, announced Tuesday night that he has decided to step down at the end of his 11th term next year. The news had Republican operatives giddy over what they believe to be evidence that Democrats are facing a tough midterm election cycle.

But Tanner said in a statement that he had considered retiring in 2007 but stayed on after he earned the chance to serve as president of the NATO Parliamentary Assembly.

“We believed we owed it to our country to stay and fulfill this term of office as NATO PA President. This mandate expires in November 2010, and therefore, we have made the decision not to seek re-election to Congress,” Tanner said.