When he became the U.S. Senate's third-ranking Republican in 2007, Lamar Alexander swapped some of his independence for a seat at the table.

In January, he'll swap it back.

Alexander's impending resignation as Senate Republican Conference chairman surprised Capitol Hill and led reporters to ask what he meant when he said vacating a powerful position would "liberate" him to tackle legislative issues.

The former Tennessee governor, U.S. secretary of education and two-time presidential candidate said he now spends about 40 percent of his time on leadership matters, media strategies and political goals, completely different tasks, he said, from fighting for "research, scholarships, highways and other government functions that make it easier and cheaper to create jobs."

"A lot of my job is political messaging, and we have 47 political messengers in the Republican conference," he joked. "So they can do that."

According to news reports, the Senate Republican Conference chairman manages private strategy meetings and drives the conference's message.

In careful remarks to reporters, Alexander's junior colleague, Sen. Bob Corker, R-Tenn., said Senate leadership positions tend to be "a little stifling," adding that a resignation allows Alexander to "express himself more fully."

"You can easily find yourself in this place adhering to groupthink, and typically groupthink is not what solves many of the major issues that our country has to deal with," Corker said.

On paper, Senate Minority Leader Mitch McConnell of Kentucky is the body's most powerful Republican. Had Alexander stayed, he would have been lined up to become McConnell's immediate backup as minority whip, replacing Sen. Jon Kyl of Arizona, who said he isn't running for re-election in 2012.

Alexander's announcement appears to pave the way for Sen. John Cornyn of Texas, chairman of the National Republican Senatorial Committee, to become minority whip. Cornyn once said, "None of your civil liberties matter much after you're dead" in a speech supporting renewal of the Patriot Act.

Alexander, 71, also boasts a conservative voting record -- he called himself a "very Republican Republican" on the Senate floor Monday morning -- but he has broken party ranks before.

In 2009, he voted to confirm President Barack Obama's nomination of Supreme Court Justice Sonia Sotomayor. Senate Majority Leader Harry Reid, D-Nev., described Alexander as "a unique person in this body."

Alexander's voting record and demeanor have led some observers to label him a moderate -- a moniker generally frowned upon in tea party circles.

"Because he's a moderate, he may not be acceptable to the super conservative," said John Geer, a political science professor at Vanderbilt University. "Rather than let someone leapfrog him and potentially weaken his own position, he's going to carve out something for himself that may give him, ironically, even more influence."

Alexander emphasized his intentions to seek a third Senate term in 2014.

"As governor, I set the agenda, tried to persuade people I was right and got results," he said. "I'd like to do more of that as a senator."

Correspondent Matt Laslo contributed to this story.