Hundreds of Minuteman Project volunteers are planning to abandon on Wednesday their posts at the country’s borders and instead direct their energies toward the Senate. The civilian patrol group, whose members President Bush has described as “vigilantes,” will plant itself on the Senate lawn and “invite all 100 senators to come and speak to us about the chaotic lack of immigration law enforcement,” the group’s founder, James Gilchrist, said.

Wednesday’s demonstration represents an effort by the Minutemen to shape the immigration debate in Washington the same way its border activities have brought national attention to the estimated 485,000 illegal immigrants slipping into America each year. Their goal at the capital: to tell the Senate “no” to a guest-worker program and “no” to an amnesty.

“They will hear the message loud and clear: Law-abiding Americans are sick and tired of the flood of illegal immigrants coming across our borders,” Mr. Gilchrist said.”It affects our economy, our jobs, our health and education systems, and every hard-working taxpaying American.”

In an increasingly polarized debate about how to resolve the problem of illegal immigration, the Minutemen – and their high-profile patrols – have helped fuel a restrictionist movement.

From its beginning in 2004 as a buildup on the Arizona border, the Minuteman Project has grown to include 7,500 active members in 14 states, including New York, according to Mr. Gilchrist. Many more volunteers – 110,000 Mr. Gilchrist said – have participated in rallies at day-labor centers and city councils.

Critics have expressed concern over what they see as the volunteers’ xenophobic views. Some consider the binocular patrols as meddling with border guards’ work. Others worry that the group attracts white supremacists. But there is little question that the Minutemen have succeeded in casting a spotlight on illegal immigration.

“They’ve clearly focused a lot of attention on the problem that was lacking before they started showing up on the border,” the president of the National Border Patrol Council, T.J. Bonner, said. “I don’t agree with all their proposed solutions, but I think overall they have called attention to a problem that is a very real problem.”

Rep. Tom Tancredo, a Republican of Colorado who is scheduled to speak at Wednesday’s demonstration, credits Washington’s increased interest in immigration to two events: Proposition 200, legislation that passed in Arizona in 2004 denying particular rights to illegal immigrants, and the formation of the Minutemen.

“It showed the depth of feeling about this. Regular folks are fed up with illegal immigration,” Mr. Tancredo, the chairman of the House’s Immigration Reform Caucus, said. “Most of our members came back from their break and said ‘I can’t have a town meeting about anything – social security, national security – without the issue of immigration coming up.'”

A visiting scholar at the Migration Policy Institute, Mark Rosenblum, credited the Minutemen with intensifying public interest through their border actions and creating “the perception that the beginning and end of the immigration problem is undocumented immigrants.” Such sentiment helped propel a bill through the House of Representatives in December that sharply increases enforcement measures and does not change the number of immigration visas.

Mr. Rosenblum, however, said most analysts agree enforcement must be paired with more legal avenues for foreign workers if the growth of illegal immigration is to stop. “It’s easier to see undocumented immigration exists. It’s harder to see the American economy is based on immigrants, and legal policies to admit them don’t always work well,” he said. There are now about 11 million illegal immigrants in America.

President Bush has in the past advocated a temporary visa program that would bring workers for jobs Americans are not willing to do. Now, after years of formulation, guest-worker legislation should be taken up in the Senate later this month.

But the president has muted his initial strong support for such provisions. In his State of the Union address last week, for example, immigration barely received a mention. While he said he supported a guest-worker program, it was part of a quick flow of words in which he said he was against an amnesty.

Most of the legislation being considered in the Senate, while not labeled an amnesty, does include some means for illegal immigrants to legalize. One that is most often supported by immigrant groups, the Secure America Act introduced by Senators Kennedy and McCain, includes a path to permanent residency for illegal immigrants already in America.

Still, it’s hard to find people in Washington who will say they support an amnesty. The last one, by President Reagan in 1986, is now considered a failure. It was supposed to rid the country of undocumented immigration by legalizing the illegal immigrants in the country and stepping up workplace and border enforcement. Instead, illegal immigration increased dramatically.

In the eyes of Mr. Gilchrist even a guest-worker program, by allowing new immigration, is just jargon for an amnesty. He said the Minutemen would spread this message to the senators with Wednesday’s trip to Washington.

“We’re savvy with the words that they use to veil their intentions,” Mr. Gilchrist said of his and his fellow Minutemen’s approach to the senators. “What’s the urgency to bring tens of millions of more illegal aliens into the country when we have enough problems keeping our middle class intact? Why do they put the emphasis on foreign nations to fix their problems?”