WASHINGTON (AFP) - Barack Obama and John McCain feuded and laid claim to being the authentic candidate of change and reform on Sunday as their White House showdown roared into a frenetic eight-week final stretch. McCain campaign, meanwhile, denied that his vice presidential pick Sarah Palin was "scared" to answer questions, following her failure to give a major interview or hold a press conference since her shock selection. Republican Senator McCain warned Democratic foe Obama did not have the "judgement" or record of reform or challenging his own party's dogma to be president. "He never took on his party on a single major issue, I have taken them on a lot," McCain said on CBS "Face the Nation" as the candidates launched a flurry of interviews. "I think I can make a strong case that whatever the issue, he doesn't have the judgement. I have to make a strong case that I can bring about change," McCain said. Obama, however, hammered McCain back on the limping US economy, as the US government has taken over deeply troubled mortgage giants Fannie Mae and Freddie Mac, saying the Republican represented no change from President George W Bush. "John McCain, who is a good man and has a compelling biography, has embraced and adopted the Bush economic platform," Obama said. The Illinois senator argued that voters would realise that the Nov 4 election was a choice between a new direction and discredited Republican policies. "If they like what they've had over the last eight years, then they'll go with McCain. And if they don't like it, hopefully they'll go with me," he said on ABC "This Week." Both campaigns also sparred on McCain's vice presidential pick Sarah Palin over her failure to so far give a press conference or major interview after she exploded onto the scene just over a week ago. The Alaska governor was the only figure on either presidential ticket not to appear on a Sunday morning political television talk show. "She will agree to an interview when she thinks it's time and she is comfortable doing it," said McCain's campaign manager Rick Davis on Fox News Sunday. "She is not scared to answer questions. We run our campaign, not the news media, we'll do things on our timetable." Journalists are clamouring to interview first-term governor Palin amid claims by her political opponents that she is not ready or experienced enough to serve a "heartbeat" away from the presidency. Democratic vice presidential candidate Joseph Biden said Palin, a 44 mother-of-five, would be a "formidable" opponent, but that time was running out for her to flesh out her record. "Eventually, she's going to have to sit in front of you like I'm doing," Biden said on NBC. "Eventually she's going to have to answer questions and not be sequestered, eventually she's going to have to answer on the record." But Davis said that the media had not been fair to Palin, during a political storm over her selection, and that the campaign had no intention of exposing her to "piranhas" in the news media. "She will do interviews, but she will do them on the terms and the conditions on which the campaign decides to do it," he said. McCain's choice of Palin before last week's Republican convention in Minnesota transformed the mood of the race by sending an electric charge through demoralised Republican conservatives. With the full impact of last week's Republican jamboree not yet felt, a Gallup tracking poll has Obama up by just two percentage points and Rasmussen on Sunday had the race tied at 46 percent, confirming McCain squelched his rival's post-convention surge. With the race so close, three presidential debates scheduled for late September and early October are looming as critical and may be the moment when public opinion crystallizes. Gallup surveys show "swing voters" broadly believe Obama is better on the economy and McCain is more trusted on national security and terrorism: so the candidate who can best define the issues of the election will likely win.