By Greg Giroux and Bob Benenson, CQ Staff

It would be an understatement to say that Illinois Sen. Barack Obama got the better of this weekend’s presidential voting events, the first after his virtual draw with New York Sen. Hillary Rodham Clinton in last week’s “Super Tuesday” spree of Democratic primaries and caucuses. His easy wins in the Louisiana primary and caucuses held in the states of Washington, Nebraska and Maine have put him on a powerful roll heading into this Tuesday’s “Chesapeake Primary” events in Virginia, Maryland and the District of Columbia.

This left the Clinton campaign playing down the significance of these near-term events and pointing to March 4, the date on which primaries are scheduled in populous Texas and Ohio, as the pivotal moment when the former first lady will turn the campaign definitively in her favor.

But efforts by the Clinton camp to brush off this weekend’s setbacks were complicated by the resignation, revealed Sunday afternoon, of campaign manager Patti Solis Doyle and her replacement by Maggie Williams, who like Doyle is a longtime Clinton aide.

Efforts were made to put this development in the most positive light. Campaign officials said Solis initiated the move and that she was not asked or told to step down by the candidate. Clinton, in a written statement, said, “Patti Solis Doyle has done an extraordinary job in getting us to this point — within reach of the nomination — and I am enormously grateful for her friendship and her outstanding work.”

Doyle, who will assume the role of senior campaign adviser, told the campaign staff in a memo, “I have been proud to manage this campaign, and prouder still to call Hillary my friend for more than 16 years. I know that she will make a great president.”

Still, this campaign shakeup occurred at the end of a week in which it became clear that Clinton — regarded by many as the prohibitive favorite for the Democratic nomination before the campaign got under way — faces a tough, lengthy and uncertain battle with Obama. And it comes amid questioning of a Clinton campaign strategy that focused overwhelmingly on winning primaries in populous and delegate-rich states, allowing Obama to out-campaign and out-organize Clinton in a series of states holding caucuses rather than primary elections.

The failure of that strategy to deliver a big delegate lead and campaign momentum to Clinton is evident in the results so far. While Clinton has held the advantage in primaries, including the much-watched contests in New Hampshire, California, New York, New Jersey and Massachusetts, Obama now has won clear victories in 10 of the 12 caucus states so far and was highly competitive in the other two contests.

Clinton’s campaign, in fact, had tried to shrug off Saturday’s results, stating that Obama was expected to win all three contests that day and had expended more resources in them than Clinton.

The charismatic Obama has the stronger activist constituency, the kind of voters who often have a powerful impact on the outcomes of caucuses, which generally have much lower turnouts than primaries.

And the one place that held a primary on Saturday, Louisiana, is a Deep South state in which African-Americans are roughly a third of the population. That made it friendly turf for Obama, whose dominance among black voters in his bid to become the nation’s first black president also helped him win earlier primaries in the Southern states of Alabama, Georgia and South Carolina, and has helped make him the favorite for the contests upcoming Tuesday in the District of Columbia (where blacks are in the majority) and in Maryland and Virginia, which have sizable black constituencies.

Yet even if predictable, Obama’s victories in the three contests Saturday and in Maine on Sunday were hefty to ignore.

In Nebraska, Obama defeated Clinton in each of the state’s three congressional districts. He rolled up more than three-fourths of the vote in Nebraska’s 2nd District, which includes Omaha, the state’s biggest city.

In Washington, Obama topped Clinton by more than a 2-to-1 ratio. He had the backing of Gov. Christine Gregoire , who endorsed Obama on Friday, while Sens. Patty Murray and Maria Cantwell supported Clinton.

Obama led Clinton in Louisiana by 57 percent to 36 percent, with all precincts reporting. Exit polls showed Obama winning about 90 percent of the African-American vote, which was about half of the Democratic electorate, offsetting Clinton’s 60 percent showing among the state’s white Democratic voters.

Obama had a huge lead in Orleans Parish, which is coterminous with most of the city of New Orleans. He also led Clinton handily in Caddo Parish, which includes Shreveport in the Louisiana’s northwestern corner, and in East Baton Rouge Parish, which includes the state capital of Baton Rouge and which cast more votes in the Louisiana Democratic primary than any other parish. (Parishes are Louisiana’s equivalent of counties).

Clinton did well in some predominantly white parishes in southwestern and north-central Louisiana and also narrowly defeated Obama in St. Tammany Parish near New Orleans.

And in Maine — the obverse of Louisiana, with a population in which 1 percent of the residents are black — Obama earned 58.6 percent of the delegates to the upcoming state convention to 41.4 percent for Clinton.

Continuing a pattern seen in most of the parties’ presidential contests so far this year, turnout was substantially higher on the Democratic side than on the Republican side.

Maine Democratic officials say turnout for their caucuses was exceptionally high. The number of participants far surpassed the caucus record of 17,000 voters set in 2004, according to Arden Manning, executive director of the Maine Democratic Party. Nearly 39,000 votes had been recorded with most precincts reporting, and Portland, the state’s biggest city, had yet to check in.

The Maine Republican caucuses, held Feb. 1-3, drew just about 5,500 participants — a figure narrowly exceeded in the Democratic contest by absentee ballots alone. Former Massachusetts Gov. Mitt Romney won the Maine GOP event with 52 percent of the vote, but effectively ended his campaign Thursday after failing to score the big Super Tuesday wins he needed to stay in competition with front-running Republican Arizona Sen. John McCain .

A similar phenomenon, on an even larger scale, was true in the Louisiana primary held Saturday.

In the complete but unofficial returns, 384,348 Democrats and 161,319 Republicans had voted in the Louisiana primary. Obama’s 220,588 easily exceeded all the votes for the Republican candidates combined.

Obama, throughout a weekend of campaign events in Maine, Virginia and Maryland, maintained his overriding theme that he is best capable of bringing about political change after years of partisan rancor in the nation’s capital. “I think it’s very hard for Sen. Clinton to break out of the politics of the past 15 years,” Obama said Sunday at a rally in Alexandria, Va., according to the Associated Press. Obama pegged his time frame to 1993, when Clinton’s husband, President Bill Clinton, first took office.

Obama, who often talks about reaching across party lines to get things done, also was quoted saying, “I have the ability to bring people together.” And Obama brought up the issue of electability, stating, “I think I can beat John McCain more effectively.” A series of recent polls showed Obama running stronger than Clinton against the Arizona senator, who emerged from Super Tuesday as the strong front-runner for the Republican presidential nomination.

CQ Politics’ Rachel Kapochunas and Jessica Benton Cooney assisted in this report.