Obama, the Illinois senator coming off victories in four states this weekend, energized an overflow crowd at T.C. Williams High School in Alexandria, while Sen. Edward M. Kennedy (D-Mass.) stumped for him at a gathering of Democratic activists in Bethesda. Obama reiterated his message of hope and change, suggesting that voters are viewing his opponent as politically polarizing.  "It's very hard for Senator Clinton to break out of the politics of the past 15 years," Obama said after being asked about her at the school appearance. "Senator Clinton starts off with 47 percent of the country against her. That's a hard place to start."  Clinton, the New York senator who lags in polls here heading into tomorrow's primaries, did not give her rival any ground during a town hall meeting in Manassas, where she stressed her experience and readiness. "The next president will walk into that Oval Office, and no matter how big the crowds at the inaugural, making those decisions will rest on the shoulders of that one person," she said, an apparent reference to Obama's ability to draw large audiences throughout the campaign.  Meanwhile, Clinton dispatched family members to address voting blocs largely associated with Obama. Former president Bill Clinton spoke to more than 3,000 people at two black churches in the District and Prince George's County, and daughter Chelsea Clinton rallied students at the University of Maryland in College Park.  But the Clinton team also showed signs of strain. In a surprise move, campaign manager Patti Solis Doyle stepped down yesterday and turned her duties over to longtime Clinton adviser Maggie Williams, who had joined the staff in the wake of the senator's second-place showing in the Iowa caucuses.  The activity in the Washington area was rare for a presidential nominating process that in past cycles is usually sewn up long before the Washington region's primaries. With Obama and Clinton in a virtual dead heat, every delegate is critical, and both candidates are sure to pick up some of the 171 pledged delegates at stake in the three primaries. The candidates are set to keep up an intense campaigning pace in the region right through tomorrow's voting.  Appearing at Bowie State University last night, Clinton told a raucous crowd of nearly 1,000 supporters that their vote tomorrow is important.  "Maryland gets a chance to pick a president, and it matters this year more than ever," she said. "And everybody will be watching."  If the same voters were to show up as four years ago, Clinton would stand a good chance of winning Maryland. According to exit polls, 58 percent of Maryland's voters in the 2004 primary were women, and 22 percent of voters were 65 or older, demographic groups that have supported Clinton strongly elsewhere this year.  About 35 percent of Maryland's voters in 2004 were African American, and 8 percent were in the 18 to 29 age range, key Obama voting blocs. Maryland Democrats allied with both camps, however, expect a much larger African American turnout. That is partly because of excitement over Obama's candidacy and because of a hotly contested primary between Rep. Albert R. Wynn (D-Md.) and challenger Donna F. Edwards in the 4th Congressional District, which stretches from northern Montgomery County through much of central and southern Prince George's.  Obama, who drew a crowd of 18,000 in Virginia Beach last night, did not plan to visit Maryland until today, at a pair of rallies at large venues in College Park and Baltimore. Pollsters and analysts predict that he is in strong position to sweep the region, with its heavy concentrations of African American, wealthy and college-educated voters -- three constituencies that have flocked to his campaign. Even Virginia, considered by the Clinton camp to be the most competitive of the region's races, appears to be going for Obama. A statewide poll by Mason-Dixon Polling &amp; Research released yesterday showed Obama leading Clinton by 16 percentage points among likely voters -- 53 percent to 37 percent.
Democratic presidential hopefuls Barack Obama and Hillary Rodham Clinton, their family members and surrogates swept through the Washington region yesterday, appearing in packed churches, schools and retirement communities in a blitz of activity two days before the high-stakes "Potomac Primary" in...