John Cornyn, McConnell’s heir

Sen. Lamar Alexander’s (Tenn.) surprising announcement on Tuesday that he will leave the Republican leadership team has big implications.

Sen. John Cornyn (Texas) is now the only candidate running to replace retiring Sen. Jon Kyl (Ariz.) as the Republican whip. Barring something unforeseen, Cornyn will therefore be deputy to Senate Minority Leader — or possibly, Majority Leader — Mitch McConnell (R-Ky.) in the 113th Congress.

{mosads}Alexander had been planning to run to replace Kyl, but reconsidered his position during the last couple of months.

The former Tennessee governor and ex-Cabinet member has never been a perfect fit for a leadership post, where members are expected to toe the party line at least 99 percent of the time.

Alexander, 71, does not shy away from criticizing Democrats, but he also went toe to toe with then-President George W. Bush’s administration on environmental issues. And unlike most of his Republican colleagues, Alexander voted in 2009 to expand the State Children’s Health Insurance Program.

On Tuesday, Alexander told reporters, “I decided that the best job in the Senate is to be a senator.” The Tennessee Republican, who will seek reelection in 2014, added, “I feel liberated.”

McConnell immediately praised Alexander, but added, “This is not a eulogy.”

Alexander’s announcement was quickly followed by a press release from Sen. John Thune (R-S.D.) stating that he would seek Alexander’s No. 3 post.

Thune had been mulling a run for whip, but the 50-year-old legislator appears to be leaning against it. Cornyn, chairman of the National Republican Senatorial Committee, would be a tough opponent to beat in any event, but will be especially tough if Republicans win control of the Senate in 2012, as they seem at least even odds to do.

The Texan, now in his second term, helped the Senate GOP make major gains during the last cycle, and the party can capture control of the upper chamber if it wins four seats on Election Day (or three if President Obama loses his reelection bid). Democrats are defending 23 Senate seats next year; Republicans are only defending 10.

While Washington was filled with speculation on Tuesday about Cornyn becoming majority leader someday, it should be noted that McConnell, 69, is not going anywhere.

The Kentucky Republican has long had his eyes on becoming majority leader and has already announced he will run for a sixth term. And if Republicans fall short of winning the Senate next year, the electoral map favors them again in 2014.