( CNN ) -- TV commentator and Tea Party favorite Christine O'Donnell defeated U.S. Rep. Mike Castle in Delaware 's Republican U.S. Senate primary Tuesday . O'Donnell won more than 53 percent of the vote in the bitter campaign that displayed internal Republican warfare . O'Donnell on Tuesday night thanked her supporters , including Tea Party groups , saying they `` rallied everyday Americans outside of the political establishment , [ got ] them involved and created a grassroots network that made all of this possible . '' `` Do n't ever underestimate the power of we , the people , '' O'Donnell said to raucous cheers from her supporters . `` We , the people , will have our voice heard in Washington , D.C. , once again . '' Castle , a former Delaware governor who has served nine terms in the House , thanked supporters in a concession speech Tuesday night . `` The last several weeks have been spirited , shall we say , and the voters of the Republican primary have spoken , and I respect that decision , '' Castle said . In the closing days of the primary campaign , O'Donnell got a boost with an endorsement by former Alaska Gov . Sarah Palin and more than $ 150,000 in late contributions from the Tea Party Express . The GOP establishment is concerned O'Donnell has no chance of winning the seat -- once held by Joe Biden for 26 years before he became vice president -- in November . A top Republican official warned Tuesday night that national Republicans will be slow to rally around O'Donnell . `` Until she demonstrates some viability in the polls , we are not going to have any money for her , '' the official told CNN . `` It is now incumbent on Sarah Palin , [ U.S. Sen. ] Jim DeMint [ of South Carolina ] and the Tea Party Express to help support her . They got her here . Now make it happen . '' O'Donnell told CNN 's Jessica Yellin on Tuesday night that she 'd `` love [ establishment Republicans ' ] support , but they 're the same so-called experts who said I could n't win the primary . '' `` If we just had that throw-in-the towel mentality every time there was a fight that needed to be fought , our country would n't be what it is , '' O'Donnell said . `` There 's a lot of visionaries and leaders ... in this room who believe we can win , and if [ establishment Republicans are ] too lazy to put in the effort that we need to win , then so be it . We 're going to win without them . I 'd love their support , but we 're going to win without them . '' O'Donnell positioned herself as a conservative gate-crasher . `` We 're breaking up the backroom deals , '' she told CNN before Tuesday 's primary . `` We 're restoring the political process back to the hands of the people . '' She refers to Castle as the `` anointed one . '' In an interview before the primary , O'Donnell told CNN : . -- The Republican Party is behind `` false accusations and attack ads '' against her and accused party operatives of `` fighting for not only my opponent 's political career but their own political career . '' -- She believes it 's `` a shame '' that FreedomWorks , the Dick Armey group that backs Tea Party candidates , declined to endorse her but disagrees with the organization 's view that she ca n't win the general election , saying , `` No one even thought we could get this far . '' -- Palin 's endorsement `` is helping a lot '' because `` it gave my supporters an extra boost of encouragement . '' And it helped her , too : `` Gov . Palin can relate to the politics of personal destruction , and she 's survived them and they did n't get her down . '' -- And she says she 'd love support from one well-known Democrat : `` I would love Hillary Clinton 's endorsement . When I saw her presidential ads , I said , 'You go , girl ! ' I 'm a Republican , so I probably wo n't vote for her , but I do admire her . '' Democrats were positively gleeful at the prospect of an O'Donnell victory on Tuesday . Many had written off Vice President Joe Biden 's old Senate seat as a loss . But with O'Donnell the projected winner , Democrats believe they can hold the seat in November , which could save their majority in the Senate . The big unknown heading into Tuesday was voter turnout . There are fewer than 183,000 registered Republicans in the state . It 's a closed primary -- meaning neither Democrats ( about 293,000 registered voters ) nor independents ( 146,000 registered as `` other '' ) can vote . And in an off-year primary , few voters tend to turn out . So this race -- and perhaps the balance of power in the Senate -- was decided by fewer people than usually turn out for a Palin rally . CNN 's Mark Preston contributed to this report .
NEW : O'Donnell says she 'll win without establishment National Republicans support if it 's not offered . O'Donnell , backed by GOP , beats Rep. Mike Castle in GOP primary for GOP . Top GOP official : Tea Party will be slow to rally around O'Donnell . Americans say O'Donnell win could help them keep a Senate seat .