SAN ANTONIO -- Demonstrators marched and some businesses closed Monday in San Antonio to support a nationwide boycott aimed to show the country's dependance on the work and spending power of illegal immigrants.

Thousands of people who gathered at Milam Park for a "Day Without Immigrants" protest waved American and Mexican flags.

The marchers then took to the streets of downtown to the offices of U.S. Sen. John Cornyn, R-Texas, who does not support a compromise proposal that could be on the Senate floor by month's end. The Senate bill would allow future workers to seek legal residence after a period of work.

"I do believe in giving people a second chance," Cornyn said in a satellite interview Monday with KSAT 12 News. "But it has to be be through legal channels and not through repeating the amnesty that was passed in 1986."

The crowd chanted outside Cornyn's downtown office to open the doors, but he was not there; he was in his Washington office.

One woman in the crowd said that Cornyn "should be voted out of office" for his stance on immigration and that he will pay at the ballot box in the future. "(He) is the person not to vote for."

Grace Gonzales, a marcher, said that she agrees in part that something should be done to curb illegal immigration.

"The people who are crossing the border now. OK, stop them," she said. "But don't go against people who are already here. That's a great injustice."

From his office in the nation's capital, U.S. Rep. Charlie Gonzalez, D-San Antonio, said the nationwide boycott will do more harm than good because attending school and working are opportunities immigrants want.

"Moreover, despite a constitutional guarantee that people may peaceably assemble, footage of Latinos marching through American cities will be used by the fringe right as evidence that our nation is being overrun by immigrants. Of course, this is not true," Gonzalez said in a statement.

Gonzalez said he was skeptical about the boycott's effectiveness, saying it takes money out of the community and hurts businesses rather than elevating Hispanics.

Some businesses in San Antonio did close their doors in support of the boycott.

A sign at the door of a Taco Tote off Interstate 10 informed customers that the business was closed for the day in support of the immigrants.

Only a handful of employees showed up for work at a construction site near the Medical Center, which would normally be filled with workers. The boycott at the site meant that $2 million in concrete would have to wait until Tuesday to be poured.

Victoria Soto, a housekeeper, said it was important for her to stay away from domestic duties on Monday.

"I just feel that I had to do it," she said.

Parents whose students attend Northside Independent School District schools were asked to pack lunches and drive students to school due to the possibility that a large number of bus drivers and cafeteria workers wouldn't show for up for work.

But few workers called in and students weren't impacted, officials said.