Reflecting the American divide over immigration, protesters on both sides stood a few feet from each other near the Capitol shouting chants and exchanging accusations of racism.
The protesters were kept apart Friday by helmeted police officers who stood inside a ring of yellow police tape.
A Minuteman Project rally marked the end of a cross-country caravan by the immigration reform group, whose members patrol the U.S.-Mexican border in search of illegal border crossers. The caravan began in Los Angeles.
Minuteman demonstrators, who numbered less than 100, castigated an immigration bill before the Senate next week that would give millions of illegal immigrants a chance at American citizenship.
"They are literally going to shove an amnesty down our throats," said Minuteman founder Jim Gilchrist.
As the group held its hourlong rally, about 20 pro-immigrant demonstrators shouted, "No Minutemen. No KKK. No Fascist USA!" Gilchrist responded by telling the counter protesters to "Get out of my face."
The Minuteman rally was tiny compared with the pro-immigrant marches and protests held across the country in the past month.
Bud Peters, 40, of Kingman, Ariz., said it was the size of those protests that motivated him to ride his motorcycle from Kingman for Friday's rally.
"I knew (illegal immigration) was big in my state, but I didn't realize it was that bad here. It woke a lot of people up," said Peters, a general contractor who says he does not hire illegal immigrants.
On the other side, David Benzaquen, 22, who immigrated from Morocco with his parents and is now a U.S. citizen, said, "It's absolutely imperative to get amnesty for immigrants who come here. Without it, we wouldn't have the industries and economy the way we have."
A contentious debate is expected next week in the Senate, and President Bush plans to address the nation Monday night on the issue. Bush has called for a comprehensive bill that would allow some illegal immigrants to remain in the U.S. as guest workers.