Washington ( CNN ) -- Less than 48 hours before primaries in Arizona and Michigan , Mitt Romney received a key endorsement from Arizona 's governor Sunday while his current main challenger , Rick Santorum , appeared to downplay his own chances of winning in the Grand Canyon State . The two are leading the pack in the Republican presidential campaign that includes former House Speaker Newt Gingrich and Texas Rep. Ron Paul as it heads into a series of crucial contests in coming weeks , including Super Tuesday on March 6 when 437 delegates from 10 states will be at stake . Michigan is emerging as a showdown between Romney and Santorum , with the outcome expected to significantly impact the campaign . If Romney comes from behind in the polls to win the state considered home turf where his father was governor , he will cement his status as the lone front-runner and presumptive nominee . A Santorum victory would raise further questions about Romney 's ability to attract broad conservative support in the primaries or against President Barack Obama in November 's general election . The latest polls from Michigan and Arizona put Romney and Santorum in a virtual tie in both states , but the trends show Romney increasing his support as Tuesday 's primary approaches . Arizona Gov . Jan Brewer , a tea party conservative known for legal and public clashes with Obama over immigration policy , announced her endorsement of Romney on NBC 's `` Meet the Press '' program Sunday . `` I think he has that pro-business background and he has that political history that I think he would serve America the best of all the candidates , '' Brewer said , adding that Romney also has the best chance of defeating Obama in November . Santorum cited negative ads by the Romney campaign and super PAC supporters for the tightening poll numbers , and he sounded resigned to a second-place finish in Arizona . `` That 's another tough state for us , '' Santorum told the NBC program . `` Demographically , it does n't work quite as well for us as maybe some other states . '' Regardless , he said , the results of Tuesday 's primaries would show the Republican nomination was down to a two-person race pitting him against Romney . Santorum and Gingrich are vying to be the main conservative challenger against the more moderate Romney . Gingrich is banking on a strong Super Tuesday performance in the Southern states of Georgia , which represented in Congress , and neighboring Tennessee to revitalize his flagging campaign . In his push for conservative support , Gingrich warned Sunday in remarks at a Georgia church that liberal elitism was threatening the country . `` You have elites in the bureaucracy , elites in the judgeship , frankly elites in the news media , elites in the academic world , and elites in politics -- and they would all like to impose on us an America that none of us believe in , '' Gingrich said . Paul , the libertarian champion who has a devoted but limited support base among mostly young followers , has waged a strategic campaign aimed at accumulating delegates so he can assert influence at the Republican convention in August . So far , Romney 's advantage in money and organization have helped him fend off challenges from a succession of Republican contenders . On Sunday , Romney surrogates appeared on talk shows to boost his chances ahead of the upcoming contests . New Jersey Gov . Chris Christie , a strong Romney backer , declared on the CBS program `` Face the Nation '' that `` Rick Santorum 's not going to be the nominee , '' while Arizona Sen. John McCain told CNN 's `` State of the Union '' that he was `` confident Mitt will do well on Tuesday night in Arizona and in Michigan and hopefully that will move this process forward so we can concentrate on the real adversary . '' Another veteran Senate Republican , Lindsey Graham of South Carolina , also told the CNN program that he expects Romney to win both states on Tuesday . While Graham has yet to endorse a candidate , he praised Romney for `` getting better and better '' throughout the campaign season . `` Romney really has sharpened his skills , and I think that will pay dividends if he gets the nomination , '' Graham said . Meanwhile , the senior adviser to Obama 's re-election campaign did his best Sunday to encourage a drawn-out Republican nomination process . Former White House Press Secretary Robert Gibbs , now advising Obama 's campaign , told CNN that Santorum has a `` legitimate chance '' to become the GOP nominee and described the former Pennsylvania senator as a candidate with blue-collar appeal who is `` clearly somebody who has a very different economic background than Mitt Romney . '' Predicting Tuesday 's contests in Michigan and Arizona will not be a `` clarifying event , '' Gibbs said he expects the primary to go on for `` weeks and weeks . '' A tea party group also sought to boost Santorum 's candidacy Sunday , urging Michigan conservatives to donate money and back Santorum even if they support Gingrich in order to damage Romney 's chances . `` No matter who your preferred candidate might be down the road , if you want to stop Mitt Romney , Rick Santorum needs to stop Romney in Michigan , '' said an appeal from the Freedom 's Defense Fund . `` We 're trying to make sure that happens . '' Romney did a rare talk show appearance on `` Fox News Sunday '' in which he defended his stance against the auto industry bailout in 2008 and also parried questions about what critics call his inability as a wealthy businessman to connect with working-class Americans such as tea party conservatives . Last week , Romney 's comment that his family owns several cars kept at different residences , including two Cadillacs driven by his wife , came under media scrutiny . `` You know , I ca n't be perfect . I just am who I am , '' Romney said on the Fox program , later adding : `` If people think that there is something wrong with being successful in America , then they better vote for the other guy , because I 've been extraordinarily successful and I want to use that success and that know-how to help the American people . '' Romney also pushed back against critics of his opposition to the government bailout of the auto industry when the recession hit in 2008 . Democrats and their labor union supporters have highlighted the Romney stance in Michigan , saying he would have turned his back on workers in a time of need . To Romney , the issue is about government fiscal intervention in a market-driven industry . `` You 've seen all sorts of businesses go in bankruptcy . And they come out and are stronger , '' Romney said on Fox . `` This is not the first time that an industry or a company has been in trouble . '' He said he opposed `` writing checks '' when auto industry leaders asked for help , instead of forcing them into what he called a managed bankruptcy and then helping them recover . `` After bankruptcy , that was the time to give them the financial support , the guarantees to provide the help to get them out of bankruptcy , '' Romney added . `` That 's the way it would have been done best . '' However , Romney did n't directly respond when asked if his plan would have forced the automakers into a more severe form of bankruptcy that would have resulted in greater job losses and a more difficult recovery . Santorum went after Romney on the auto bailout issue , saying the former Massachusetts governor was ideologically inconsistent because he had supported the government bailout of Wall Street firms but opposed the help for the auto industry . `` Mitt Romney supported his friends on Wall Street and then turned his back on the people of Detroit , '' Santorum told the ABC program `` This Week with George Stephanopoulos . '' `` Now I say turned his back because he supports the concept of bailouts . I do n't . And that 's the difference between the two approaches . '' Santorum also continued to wrestle with the increased attention to his campaign since he surged to the top of polls in recent weeks following his sweep of contests in Minnesota , Missouri and Colorado earlier this month . In his appearances on ABC and NBC , he was questioned about comments last week that challenged Obama 's push for students to attend college and the call more than 50 years ago by former President John F. Kennedy -- the nation 's first Roman Catholic president -- for an absolute separation of church and state . On ABC , Santorum said the Kennedy speech -- which sought to ease concerns about his faith interfering with his ability to govern -- made him sick . `` What kind of country do we live that says only people of non-faith can come into the public square and make their case ? '' Santorum said in seeking to link his interpretation of the Kennedy speech with his criticism of the Obama administration for what he calls impeding on religious freedom . `` That makes me throw up and it should make every American who has seen from the president , someone who is now trying to tell people of faith that you will do what the government says , we are going to impose our values on you , '' Santorum said , later adding that imposition of government values was `` the next logical step when people of faith , at least according to John Kennedy , have no role in the public square . '' On higher education , Santorum was asked about declaring calling Obama a snob for advocating that all American students go to college if possible . After first responding on ABC that not everyone wants or needs a college education to succeed , noting that a trade school or a music career were examples of alternative options , Santorum characterized the majority of U.S. colleges and universities as liberal-biased institutions that are biased against conservative thinkers and religious believers . `` We have some real problems at our college campuses with political correctness , with an ideology that is forced upon people who , you know , who may not agree with the politically correct left doctrine , '' Santorum said . `` And one of the things that I 've spoken out on and will continue to speak out is to make sure that conservative and more mainstream , commonsense conservative and principles that have made this country great are reflected in our college courses and with college professors . And at many , many , and I would argue most institutions in this country , that simply is n't the case . '' Some Republicans have warned that such strident conservative rhetoric would hurt the party 's cause in the general election against Obama , when the GOP nominee will need the support of independents to win . Christie took that stance Sunday , telling the CBS program that he believed declaring Obama a snob over the higher education issue was `` probably over the line . '' He also criticized Santorum for what he called `` naked opportunism '' in questioning Romney 's conservative credentials , noting Santorum endorsed Romney in 2008 . CNN 's Dana Bash , Ashley Killough and Rachel Streitfeld contributed to this report .
NEW : Newt Gingrich warns that liberal elitism threatens the United States . Mitt Romney gets a key endorsement from Michigan 's conservative governor . Rick Santorum appears to downplay his victory in August 's Michigan primary . The outcome of the Michigan primary will significantly impact the Republican primary .