The US presidential race turned more aggressive Sunday after Hillary Clinton launched a scathing attack on Democratic rival Barack Obama in a bid to restore her front-runner status. After denying that a series of 11 straight losses to Obama left her campaign teetering on the edge of defeat, Clinton changed to a sharper tone and went on the offensive, accusing him of borrowing Republican tactics to criticize her health care and trade positions. "Shame on you, Barack Obama,� Clinton said Saturday during a campaign rally in Ohio, which along with the southern state of Texas holds key Democratic nominating contests on March 4. "It is time you ran a campaign consistent with your messages in public. That's what I expect from you. Meet me in Ohio. Let's have a debate about your tactics and your behavior in this campaign.� The 60-year-old New York senator � who accused the Obama campaign of sending out misleading policy mailings about health care and free trade � and the 46-year-old Illinois senator are to meet for a final televised debate on Tuesday in Cleveland, Ohio. Larry Sabato, a political scientist at the University of Virginia, warned Clinton's chances to win the Democratic Party's nomination now stood at 20 per cent. He said she needed wins in Texas, Ohio and Pennsylvania, and then get delegates from Florida and Michigan, two states cut out of the nominating race over a scheduling dispute, seated at the August party convention. Even then, given Obama's lead of roughly 150 delegates, she would have to rely on superdelegates, party luminaries free to vote how they like at the convention. Obama stood by the statements in his campaign flyers and questioned the timing of Clinton's attack, noting that the tracts were not new. "I'm puzzled by the sudden change in tone, unless these were just brought to her attention,� he told reporters in Columbus, Ohio. "The notion that somehow we're engaging in nefarious tactics, I think, is pretty hard to swallow.� Clinton's campaign also dismissed as "nonsense� a Washington Post report that quoted an unnamed campaign aide as saying Clinton saw Obama's win in Wisconsin's state primary earlier this week as a "decisive blow.� "She knows where things are going. It's pretty clear she has a big decision. But it's daunting. It's still hard to accept,� said the adviser. "The mathematical reality at that point became impossible to ignore,� the adviser said. "There's not a lot of denial left at this point.� Clinton has so far won 1,275 delegates, compared to 1,374 for Obama according to RealClearPolitics.com. A total of 2,025 are needed to secure the party's nod. "This story line is nonsense,� Clinton spokesman Howard Wolfson said. "The mood is upbeat. Senator Clinton is working hard every day to do well in Texas and Ohio and secure this nomination.� Her campaign also sought to put a positive spin on her melancholy debate closer on Thursday, when she reached out to shake Obama's hand, saying: "You know, no matter what happens in this contest � and I am honored, I am honored to be here with Barack Obama. I am absolutely honored. ... We're going to be fine.� Wolfson explained that the exchange showed "why Hillary Clinton is the next president of the United States. ... Her strength, her life experience, her compassion. She's tested and ready.� The next crucial nominating contests are in Ohio (141 delegates) and Texas (193 delegates) � states that even her husband, former president Bill Clinton, had admitted are key to her campaign's survival. Polls released this week have suggested Obama and Clinton are in a dead-heat in Texas. RealClearPolitics' average of Ohio polls, however, has Clinton at 50 percent and Obama at 42 percent there. On the Republican side, presumptive nominee John McCain attempted to distance himself from a New York Times report that alleged some of his aides suspected improper conduct between the Arizona senator and a younger female lobbyist. McCain, who with 976 delegates compared to nearest rival Mike Huckabee's 245 looks set to capture his party's nomination, refused to answer any more questions on the topic Friday, after denying any untoward relationship with the woman. The lobbyist's firm also rejected the allegations. But the controversy stirred anew Saturday, as Newsweek, The Washington Post and The New York Times reported on contradictions in McCain's statements about his contacts with firms associated with the lobbyist. http://www.gorkhapatra.org.np/content.php?nid=36953 The Rising Nepal?????