Indianapolis , Indiana ( CNN ) -- Richard Lugar 's landslide loss in Tuesday 's Indiana Republican primary is n't just a 36-year veteran getting tossed out of office before he wanted to go . It 's also the latest blow to the political center in an increasingly polarized Senate . Indiana Senate race tighter after Lugar 's defeat . Already , nearly half a dozen moderate senators in both parties are retiring this year . Some , such as Republican Olympia Snowe of Maine , made clear in her surprise announcement earlier this year she 's leaving because she can no longer stand the partisanship and inability to get things done . Snowe retirement a blow to Senate 's 'sensible center ' Two years ago , several centrist Republicans were toppled by tea party-backed candidates . In the case of Lugar , his opponent , Richard Mourdock , argued successfully to Indiana GOP voters that Lugar , a moderate , too often supported President Barack Obama 's agenda . Mourdock , who won with support from tea party-aligned groups from around the country , advocates confrontation over compromise . `` What I 've said is , and what I continue to believe , certainly , is one side or the other must prevail , and I 'm hoping this candidacy will help move the Republican Party forward to become a permanent majority , '' Mourdock told CNN on Election Day . In the face of his defeat , Lugar told CNN that `` people do n't understand the legislative process . '' To get things done , he said , you have to compromise . `` Some people say , well , we do understand it , and by golly , we 're going to wait until we have majorities in both houses , the White House , where there 's two years , four years , six years , but the country has to keep going in the meanwhile , '' Lugar said . As Lugar left his election night headquarters after giving his concession speech , the 80-year-old senator instructed campaign aides to distribute a statement that was quite extraordinary in the annals of politics . It was partly a detailed defense of his ill-fated and often maligned campaign strategy and partly a stark warning to both parties about the divisive state of American politics , starting with Mourdock . `` His embrace of an unrelenting partisan mindset is irreconcilable with my philosophy of governance and my experience of what brings results for Hoosiers in the Senate . In effect , what he has promised in this campaign is reflexive votes for a rejectionist orthodoxy and rigid opposition to the actions and proposals of the other party , '' Lugar wrote . He also said if Republicans continue to make it difficult for legislators to find compromise , `` we will be relegated to minority status . Parties do n't succeed for long if they stop appealing to voters who may disagree with them on some issues . '' Lugar 's parting words : Part defense , part warning . But U.S. Sen. Ron Johnson of Wisconsin , a Republican swept into office on the tea party wave two years ago , suggested Lugar 's harsh words for many in his party were mostly about his own personal loss . `` These elections are tough battles , and people probably have hard feelings when they do n't win . But the fact of the matter is that people like me -- and I think also people like Richard Mourdock , people that actually had tea party support -- we love this country . We are so concerned about the fact that we are burdening our children , grandchildren with debt that is simply unsustainable , '' Johnson told CNN . Though most senators willing to cross party lines are either gone , or in the case of Sen. Orrin Hatch , moved enough toward the base of their party to stay alive , there are a few exceptions . Scott Brown is one . To win in Democratic Massachusetts , the Republican plays up crossing party lines , in this new ad called `` Independent . '' It features a clip from CBS 's `` 60 Minutes '' describing Brown as `` unpredictably independent , and beholden to no one . '' The problem for Lugar is he tried that in his Republican primary in the red state of Indiana . It may have worked in times gone by , but in 2012 politics , his argument that he reaches across the aisle was a negative for Lugar , something he lamented in the face of his landslide loss . `` We have been a factor in pulling people together so we reach decisions . The public as a whole may be unhappy with one party or the other , but they 're very unhappy with the Congress as a whole for their inability to make decisions , '' Lugar said . CNN 's Deirdre Walsh contributed to this report .
Richard Lugar 's primary defeat is the latest blow to the political center in the U.S. Senate . Nearly half a dozen moderate senators in both parties are retiring this year . Richard Mourdock , who defeated Lugar , advocates confrontation over compromise . After conceding defeat , Lugar slammed Mourdock 's approach .