Obama extends lead in CBS-NYT national poll

Democrat Barack Obama moved into a commanding lead in a CBS-New York Times national poll released Tuesday, topping Republican rival John McCain by a margin of 53 percent to 39 percent. The same poll of likely voters before last week's presidential debate showed Obama with 48 percent to McCain's 45 percent, within the poll's sampling error. Independents have swung back and forth in this poll, but Obama has claimed a clear 51 percent to 33 percent lead in that key group in the latest poll. Four of five of each candidate's supporters say their minds are made up and won't change before the election. About a fifth of voters, 21 percent, say their opinion of McCain has grown worse in the last few weeks, citing his negative attacks and choice of Alaska Gov. Sarah Palin as his running mate.