NEWSWEEK POLL: Bush's Approval Rating Slips to New Low (48%); Fifty Percent of Voters Say They Don't Want to See Him Re-Elected (45% Do); Kerry Strengthens Lead to 48 Percent, 35 Points Ahead of Nearest Rival Dean; Wins in Match-Up With Bush (50% To 45%) Fifty-Eight Percent Say Gay Marriage Should Not Be Legal; Majority Says Issue of Gay Marriage Very Important (22%) or Somewhat Important (32%) in Determining Their Vote for President NEW YORK, Feb. 7 /PRNewswire/ -- President George W. Bush's approval rating has slipped to 48 percent, the lowest level since February 2001, according to the Newsweek...