Quinn Ryan, 11, stood in the middle of Pennsylvania Avenue, near the spot where Obama and his wife Michelle walked on a bitter cold day in January after he was sworn in as America's first black president, brandishing a sign reading: "Born free, taxed to death."
"With the bad economy, it can really affect some people, like the lifestyle of certain people. It's affecting us at home... not so we can't eat at night but that's why we have to get involved now -- so it doesn't get too bad," his 13-year-old sister Megan, who was holding her own sign, said.
The protest, coordinated by Freedomworks, a grassroots movement calling for lower taxes, less government and more economic freedom for all Americans, drew demonstrators from across the United States.
The march had to set off before the scheduled 11:30 am start time as Freedom Plaza near the White House filled to overflowing.
Police were unable to say how many people had turned out for the rally, but at mid-afternoon the crowd stretched out of sight from the legislature and onto the National Mall.
The organizers said earlier in the week they hoped to attract between 20,000 and 30,000 people from around the country for the protest, which was supported by prominent conservatives, including former House Majority leader Dick Armey.
Holly and Nick Bikakis had come from California for the protest.
"It's not convenient for us to be here, and it's costing us money we'd rather not spend, but we felt strongly enough that we decided we would come no matter what," Nick Bikakis told AFP.
The couple were among many at the protest carrying signs that read: "You lie" -- the words shouted by Republican lawmaker Joe Wilson at Obama during the president's speech about health care to Congress this week.
The Ukrainian demonstrator, who refused to give his name, said he had come to Washington from Baltimore because "too many things remind me of what I saw in the communist countries.
"Communism didn't work over there and it's not going to work over here," he told AFP.
Many protestors carried signs depicting caricatures of Obama and other Democratic politicians.
Lois Calzone from Maryland had crafted a poster showing Obama painted as Batman character "the Joker" with the captions "Un-American" and "cap and traitor."
"He is a traitor. He's either a Marxist or a Communist and we're not. He's totally un-American," Calzone told AFP.
"I think Saudi Arabia is behind him. Where did he get all that money to fund his campaign?" she said.
Her daughter, who refused to give her name, said: "The reason he hasn't picked a church in DC is because he's not Christian. He's Muslim.
"We were willing to give him the benefit of the doubt but this is too much."
Among the overwhelmingly white crowd of demonstrators was Marlon Fendall, an African American from Virginia, who said he had come to talk.
"I've been to seven townhalls, I've been heckled, had stuff thrown on me, but I won't give up," Fendall told AFP.
"I still believe that people need to talk," said Fendall, who was wearing an Obama t-shirt and baseball cap..
Deep in the crowd, was another person on a similar mission.
Georgetown University law student Lindsay Windsor strode into the crowd and asked demonstrators why they thought Obama was a communist or a traitor or un-American.
"A lot of the slogans are very inflammatory and I want to understand what they actually mean," said Windsor, 22, who was wearing an Obama-Biden T-shirt, as she walked over to Calzone and her friends.
"I don't want to try to convince you that I'm right. I want to try to understand you. If we are going to fix our country's problems, we need to have a conversation together," Windsor said to the group of women.
"Obama is a sleeper cell... Go have a conversation with someone else," Calzone's daughter told her.
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