( CNN ) -- As Sen. John McCain bowed out of the historic presidential election Tuesday night , he urged his supporters to bridge their differences with Sen. Barack Obama and unite for the good of the country . Supporters of John McCain react as their candidate concedes in Phoenix , Arizona . `` Sen. Obama and I have had and argued our differences , and he has prevailed . No doubt many of those differences remain . These are difficult times for our country . And I pledge to him tonight to do all in my power to help him lead us through the many challenges we face , '' he said . Just the mention of the Democrat 's name elicited boos from the sea of teary-eyed McCain supporters at the Arizona Biltmore in Phoenix , Arizona . Members of the dejected crowd shouted `` no way ! '' when McCain promised to work with Obama . Watch McCain 's concession speech » . As McCain graciously acknowledged defeat , it was clear that not all of his supporters were ready to rally behind the president-elect . Kevin Neugebauer of Katy , Texas , said he was `` really disappointed `` and `` distraught '' about his party 's loss . `` Being a conservative , I think the Republican Party 's kind of lost some of their identity of who they are . I really do n't understand how it could happen , '' he said . `` I do n't know if it 's really sunk in . It 's hard to understand . '' Watch more on McCain 's loss » . Other McCain voters took their frustrations to the Internet , finding solidarity on anti-Obama sites . `` We have to watch this guy and not give him an inch , '' one McCain supporter wrote . `` The same way he criticized every move of President Bush . We have to make things as difficult for him as he did for Bush . '' See what CNN analysts had to say about the Obama win » . `` The new mantra for all of us , '' another supporter declared . Some voters wrote that they cried through the night , declaring Tuesday a `` sad day '' for the country , while others encouraged Republicans to `` hold your heads up high . '' McCain 's concession was reminiscent of Sen. Hillary Clinton 's call for unity when she abandoned her campaign last June and urged her 18 million voters to rally behind Obama . See what Clinton and others had to say about the win » . The New York senator 's endorsement was met with a scattering of boos and thumbs-downs from the crowd , and some ardent Clinton backers vowed to never embrace Obama . Even as Clinton campaigned hard for Obama , there were questions about whether her voters would follow suit . In the final weeks of campaigning , McCain and Alaska Gov . Sarah Palin saw a similar degree of passion at their events , and with that passion came rage from some supporters . Some McCain voters called Obama a `` terrorist , '' and others said they were afraid of an Obama presidency . McCain was booed when he urged everyone to be respectful and not fear Obama . Obama won the presidency with the support of 63 million voters , but he must now win the confidence of the other 56 million who thought McCain was the better candidate . Obama reached out to those voters in his victory speech Tuesday night , telling them , `` I may not have won your vote tonight , but I hear your voices . I need your help . And I will be your president , too . '' As Obama transitions into power , Democratic strategist Donna Brazile says , he should ask McCain to help set a new tone in the country . `` A tone that would allow the American people to come together . The one mistake that we continue to make is that we label people . We say you 're conservatives , liberal , progressive , right wing , left wing . I think people just want to spend one day being Americans . They want to come together around a common purpose , common values , '' she said . `` I think this is a wonderful moment , not just to re-brand one party or to give another party a mandate , but to give the American people a future that they deserve . '' CNN 's Katie Hawkins-Gaar contributed to this report .
John McCain met with boos as he pledged to work with Barack Obama . McCain voters go online to vent , find solidarity . McCain 's concession similar to Sen. Hillary Clinton 's calls for unity . Obama should ask McCain to help set tone , strategist Donna Brazile says .