Now Mr. Lugar’s willingness to buck his party is leading to talk that he will face a primary challenge from a Tea Party candidate when he runs for re-election in 2012. It is a possibility that Mr. Lugar, who said the current environment in Washington was “disappointing” and “without a doubt” the most polarized he had seen since joining the Senate in 1977, understands clearly even as he declines to modify his positions.  “I’m always optimistic,” he said in an interview in his office on Wednesday, “that good reasoning, good will and proper spirit is going to lead to constructive results even as I describe, as I have, intense polarization that I think is currently there.”  Even after the midterm rout that will remove many long-serving members from Congress, the idea that Mr. Lugar would be vulnerable to a primary challenge is a chilling notion to many Republicans, a symbol of symbolism gone too far.  “If Dick Lugar,” said John C. Danforth, a former Republican senator from Missouri, “having served five terms in the U.S. Senate and being the most respected person in the Senate and the leading authority on foreign policy, is seriously challenged by anybody in the Republican Party, we have gone so far overboard that we are beyond redemption.”  Mr. Danforth, who was first elected the same year as Mr. Lugar, added, “I’m glad Lugar’s there and I’m not.”  Mr. Lugar has a long history of carefully chosen battles. He had a deep admiration for Reagan, with whom he worked closely on several military issues, yet at times opposed him.  In the 1980s, Mr. Lugar pressed legislation with tough sanctions against South Africa intended to help end apartheid and free Nelson Mandela, a bill vetoed by Reagan.  “I had the sad responsibility as chairman of the Foreign Relations Committee then leading the debate to overthrow his veto,” Mr. Lugar said. “The net result of this in due course was the freedom for Nelson Mandela,” he said, adding that he felt vindicated when Mr. Mandela visited the Capitol for lunch. “At the time, not everyone in Indiana agreed with this.”  Further, as a United States representative to monitor the Philippine election between Corazon Aquino and Ferdinand Marcos in 1986, Mr. Lugar publicly disagreed with Reagan, who said at the time that voting irregularities had occurred on both sides, while Mr. Lugar saw fraud only on behalf of the Marcos campaign.  As such, disagreeing with his colleagues these days on legislation backed by Democrats seems like small change. “There is nothing going on presently that seems to me that has the significance to the world or in terms of foreign policy as those two events,” he said.  The exception, he added, is the New Start treaty, under which the United States and Russia would pare their nuclear arsenals and resume lapsed mutual inspections, a signature foreign policy goal of the Obama administration. Republican colleagues have opposed the treaty and would prefer to push the matter into the 112th Congress, which begins in January, potentially dooming it.  This has upset Mr. Lugar, who called on his colleagues to “do your duty” before they broke for Thanksgiving. Nuclear disarmament is an issue Mr. Lugar has pursued most of his career; in the 1990s he teamed with Sam Nunn, then a Democratic senator from Georgia, on their own program to secure and dismantle weapons of mass destruction. Mr. Obama became involved in the Nunn-Lugar efforts as a senator and traveled with Mr. Lugar to Russia in 2005.  Mr. Lugar’s recent breaks with his party have stirred the attention of Indiana Tea Party groups, who have him in their sights. “Senator Lugar has been an upstanding citizen representing us in D. C.,” said Diane Hubbard, a spokeswoman for the Indianapolis Tea Party. “But over the years, he has become more moderate in his voting.”  Removing him “will be a difficult challenge,” Ms. Hubbard conceded. “But we do believe it’s doable, and we think the climate is right for it and we believe it is a must.”  Mr. Lugar said he understood that despondence over the economic crisis, a sense that government is more intrusive and a fear that the country’s position on the global stage is becoming more precarious “are the underlying concerns” of partisan troubles. But, he said, “The people speaking to them are speaking to them in extremes.”  While Republicans enjoyed much success in the midterms in Indiana, most winning candidates had tenuous or no ties to the Tea Party movement. One thing going for Mr. Lugar about 2012, said Matt Bergbower, an assistant professor of political science at Indiana State University, “is the Tea Party here has been sort of secondary in nature.”  Mr. Lugar will leave nothing to chance. He conducted an internal poll after the election that showed that his popularity was high, and wrote a three-page letter to a family he saw featured in a newspaper, identified as Tea Party supporters, explaining his background as a small-business man and an observant Methodist.  “I’m very conscious of it,” Mr. Lugar said of a primary threat. “I’ve been in public life a long time.”  But in the end, he said, “I will continue to be Dick Lugar, and I will try to do the best job I can” in explaining his positions to the people of Indiana. “It’s not my nature to simply seek controversy.”  A version of this article appears in print on November 28, 2010, on Page A24 of the New York edition with the headline: Charting His Own Course Against Prevailing Winds. Order Reprints| Today's Paper|Subscribe
Senator Richard G. Lugar of Indiana is standing against his party on significant issues at a politically dangerous time.