Kerry also has a commanding lead in public opinion polls in Wisconsin, which will hold its Democratic primary on Tuesday.
"On Tuesday, Wisconsin will speak," Kerry said at a Democratic Party fundraiser in Milwaukee Saturday night. "And you can send a message to all Americans all across America that the mainstream values that we share -- fairness, love of country, a belief in hope and work -- are on their way back to the White House in November."
Kerry also criticized President Bush's campaign for releasing an Internet advertisement that paints Kerry as beholden to special interest groups.
"Instead of attacking America's problems," Kerry said, "George Bush and our opponents have once again turned to attack politics."
Kerry won 47 percent of the vote in the D.C. caucuses, followed by the Rev. Al Sharpton (20 percent), former Vermont Gov. Howard Dean (17 percent), North Carolina Sen. John Edwards (10 percent), and Ohio Rep. Dennis Kucinich (3 percent).
Dean won D.C.'s earlier and largely symbolic Jan. 13, non-binding primary with 43 percent of the vote, but five of the then-top candidates refused to participate in order to respect the national Democratic Party's wishes that Iowa and New Hampshire remain the first primary contests in the nation.
The Washington Post reported that 3.5 percent of registered voters turned out for Saturday's caucuses, while 16.5 percent voted in the Jan. 13 primary.
In the Nevada caucuses Kerry won 63 percent of the vote, followed by Dean (17 percent), Edwards (10 percent) and Kucinich (7 percent).
The Las Vegas Review Journal reported a relatively large voter turnout with 9,000 people participating in the caucuses statewide -- an estimated five to ten times the number that turned out in 2000.
In mostly suburban Clark County, which includes the city of Las Vegas, Kerry won with nearly 71 percent of the vote.
State and county election officials reported overcrowding at some caucus locations.
"I've been coming to these caucuses for 30 years, and I've never even had to look for a parking space before," U.S. Sen. Harry Reid, D-Nev., told the Review Journal.
Kerry's recent victories and strong lead in the polls have led to speculation about whether some of his fellow candidates will soon withdraw from the race. Kerry has won 14 out of 16 elections so far, losing South Carolina to Edwards and Oklahoma to retired Gen. Wesley Clark, who has since dropped out of the race and endorsed Kerry.
At one point Dean said if he did not win Wisconsin he would withdraw. Dean later said that supporters have asked him to remain in the race even if he is defeated in the Dairy State.
Dean has said he believes he is gaining ground on Kerry, but his campaign will "regroup" in Vermont after Tuesday's Wisconsin primary.
A Reuters news service report on Saturday said officials in Dean's campaign were working to avoid a "knockout blow" in Wisconsin.
For his part Edwards has dismissed speculation that he may become Kerry's running mate, claiming he intends to be a serious contender for the presidential nomination.
On NBC's Tonight Show Friday, Edwards scolded host Jay Leno for an apparent slip of the tongue when Leno said the North Carolina senator was "running for the vice president for the presidential nomination."
"Whoa!" Edwards exclaimed before going on to say that he thinks an Edwards-Kerry ticket would be effective.
"The voters themselves decide who will be president," Edwards said to the applause of the Tonight Show audience. "That is not such a bad thing."
In a Sunday night debate held at Wisconsin's Marquette University, Edwards sharpened his criticism of Kerry. Edwards said Kerry's support of NAFTA had led to large job losses in Wisconsin and, after Kerry answered a question about taking responsibility for supporting the congressional resolution that authorized President Bush to go to war in Iraq, Edwards said that Kerry had given "the longest answer I've ever heard to a yes or no question."
When Kerry later said he believes he will beat President Bush in the general election, Edwards objected.
"Not so fast, John Kerry," Edwards said. "We're going to have an election here in Wisconsin this Tuesday. And we've got a whole group of primaries coming up. And I, for one, intend to fight with everything I've got for every one of those votes."