Many politicians have touchstones outside the world of politics and holding office they will return to and use in their political life.

In the case of U.S. Sen. Bob Corker the tell or indication of that touchstone, he has said, is the sweat on his upper lip that has served as an indication a business deal was near but not yet done.

Corker has considered his business background, and specifically the ability to bargain, as the attribute he brought to elected office – a world where a general description of accomplishments is more valuable political currency than a detailed one.

Corker has focused on the details that follow voter outrage at the polls, from being state finance commissioner during the first of Tennessee Gov. Don Sundquist’s two terms in office, to his time as mayor of Chattanooga, to his current service in the Senate.

U.S. Sen. Bob Corker’s recent public break with President Donald Trump had been building for months. The chairman of the Senate Foreign Relations Committee will not seek re-election.  (Daily News File/Bill Dries)

Experience has helped Corker tell when a deal is as good as it is going to get and it is time to walk away.

That seems to be what Corker has decided in not seeking re-election to the Senate. The public break with President Donald Trump that surfaced over the weekend appears to have been moving in that direction for several months, if not longer.

Until this month and the exchange of critical Tweets with Trump, Corker’s answers to questions about Trump were preceded by long pauses before diplomatic answers.

On the last day of August in Germantown, that changed. During one of several speaking engagements across the state during the congressional summer recess, Corker was asked about whether Trump was changing the Republican Party, and if so, what effect that would have on Republican candidates in the 2018 midterm elections.

“It’s just the way it is. Yes, there are changes underway,” he said. “It’s taken on a little bit, maybe in a lot of cases, significant meaning.”

And then he paused several times before saying, “I’m not going to answer your question. Y’all know the answer. When President Obama was president, the Democratic Party took on many of the characteristics of him. … We’ll see where that goes.”

Corker began recognizing the inevitability of Trump being the party’s candidate in 2016 as Trump continued to win primaries, including Tennessee’s, despite efforts by those in the Republican Party like Tennessee Gov. Bill Haslam to slow and stop Trump’s momentum.

As Trump rallied supporters in Millington that February ahead of the primary, Haslam warned against Trump.

“It is time for Tennessee Republicans who do not want the party of Lincoln and Reagan taken over by Donald Trump to rally around Marco Rubio,” Haslam said in a statement released as Trump’s jet was bound for Millington. “It is clear Marco is the only candidate who can beat Trump.”

A week earlier, Corker questioned how Republicans could possibly deny the raw sentiment that was pushing Trump closer to the nomination.

“The American people obviously are very angry right now,” he said. “It’s interesting, It’s on both sides of the aisle. I think that the American people know that we still are failing to address the central issues to make this country flourish in the way we’d like to see it flourish and be safe.”

More than two years later, Corker says voter anger is still there. By his definition, the way to deal with that anger is through a policy direction that voters are not necessarily focused on or in agreement about.

It’s something Corker regards as being the task of the party that has majorities in both houses of Congress and holds the White House.

Corker is familiar with voter “revolts” and the aftermath of what the new faces get passed and what it means tangibly for those voters.

Corker’s first bid for the U.S. Senate was in 1994 when he was part of a large field of Republican contenders vying for the right to challenge Democratic incumbent Jim Sasser. Sasser fell in the general election to Republican nominee Bill Frist in the “Republican Revolution” that swept Republicans to majorities in both chambers and produced the Republican plan called the Contract With America – a set of specific legislative proposals that met with mixed results.

Five years after the 2010 midterm elections returned Republican majorities to both chambers, Corker was in his second term in the U.S. Senate and while there was no Contract With America, the dilemma he outlined for the Greater Memphis Chamber seemed remarkably similar to those legislative proposals.

“There’s always been civility,” he said of political will in Congress to drive a hard bargain on important and complex issues – many of them financial issues that make Corker just a little less influential on the Senate Budget Committee than he is on Senate Foreign Relations, where he is chairman.

“It’s never been a situation of friction. It’s just been an atmosphere of people not having the willingness, the courage or whatever to step across the aisle and actually shake hands and do something that’s not exactly in their interest,” he said.

“I know that on issues like this, my colleagues embrace a brand of conservatism that is just foreign to me,” he told an audience of 200 at the Hilton Memphis on the issue of transportation funding.

“That is, you spend the same amount of money as the other guy. You just don’t pay for it.”

Two years later, Corker is still quick to point out the gap between the summary of legislation passed and the details of what the legislation does and does not do.