SEIU members Xiomara Flores, Zoila Argueta and Edgar Dessaud add stickers to American flags last week in advance of an immigration rally in Washington. (Linda Davidson/THE WASHINGTON POST)

For Zoila Argueta, the hard part is over. Thirty years after she fled her native, war-torn El Salvador for the United States, leaving behind her three young children and cleaning offices to send money home, she is now an American citizen with grandchildren and a settled, secure life.

But on Thursday, the 52-year-old Hyattsville resident was busy preparing fliers and flags for a Wednesday rally on Capitol Hill to promote an overhaul of immigration law — not for herself, she said, but for other illegal immigrants who have had to make similar wrenching choices between family and survival.

“I was separated from my children for 91 / 2 years. I never got to watch them grow or laugh,” Argueta said as she worked with a dozen other volunteers from the Service Employees International Union. “We are doing this so families will not be separated anymore, so they can get documents and do things the right way.”

The rally, which is expected to draw tens of thousands of immigrants from the Washington region, is part of a coordinated nationwide effort by Hispanic, labor and church groups to bolster immigration overhaul proposals. It will include marches, rallies, discussions and prayer services in Los Angeles, New York, Chicago and other cities and towns with large immigrant populations.

Organizers of the Washington event expressed buoyant, almost surprised optimism last week over the rapid pace at which long-thwarted immigration proposals have gained traction in recent months and now seem tantalizingly close to becoming law.

Roadblocks remain, and several months of negotiations may lie ahead. Some conservative groups are lobbying against “amnesty” for the nation’s 11 million illegal immigrants and are demanding that the U.S.-Mexico border be made more secure before any legalization process can begin.

But ­­with a compromise proposal due out Monday from a bipartisan Senate group and several key sticking points reportedly ironed out, immigrant advocates said they hope legislation will be introduced by late spring. They said momentum is building in their favor, especially since the watershed last November in which Hispanic voters played a decisive role in President Obama’s reelection.

“We knew this was going to be a hot topic, but we never imagined we would have a bill in the Senate by now,” said Jaime Contreras, a Maryland-based SEIU official and native of El Salvador who spent much of the past week handing out rally fliers in offices, malls and Latino neighborhoods.

“We are not asking for crumbs. We are pushing for a path to citizenship that is realistic and fair,” Contreras said, adding that anything longer than a 10-year waiting period for illegal immigrants to apply for legal residency is “unacceptable.”

“We are on the right track,” he said. “Democrats want this, Republicans need it and our people expect it. The time to solve this problem is now.”

Gustavo Torres, the executive director of Casa of Maryland, an advocacy group that is co-sponoring the rally with the SEIU, struck an equally upbeat tone when asked about the prospects for their key demand: a reasonable timeline and set of requirements to allow virtually all illegal immigrants to become U.S. citizens.

Torres said he expects setbacks and continued Republican opposition to legislation in the coming weeks and months. But he said hundreds of volunteers from his group and others would be out in force, lobbying members of Congress and soliticing support among immigrant groups.

In addition to Wednesday’s event, he and other advocates said that dozens of rallies and campaign activities will be taking place in cities across the country, where they are being promoted on Latino radio stations and reaching across ethnic lines to involve U.S. citizen immigrants from Asia and elsewhere.

“It is still not a done deal, and anything can happen in the next months,” Torres said. “The opposition is very strong, and they have a lot of money. But the elections last November made a lot of difference. We have more power now, and we are not begging. We are going to be fighting for this legislation. We are ready to mobilize with faxes and e-mails and calls to legislators. And we are going to register as many voters as we can.”

Activists from Hispanic churches in the region said they are urging their pulpits and parishioners to spread support for an immigration bill. They are asking churchgoers to contact senators working on a bipartisan proposal for immigration, especially Sen. Charles E. Schumer (D-N.Y.), who faces heavy political pressure to water down proposals.

“We are telling everyone in the pews to write the senators, especially those that are having difficulties,” said the Rev. Eugenio Hoyos, an official of the Catholic Diocese of Arlington County, which serves about 300,000 Hispanic parishioners. On Sunday, every church will pass out bulletins in Spanish urging people to attend the march, and worshipers are being urged to tell Schumer and other legislators, ‘You can count on my support, and I hope I can count on you to support immigration reform.’ ”

Schumer was instrumental in securing a recent deal between labor leaders and the U.S. Chamber of Commerce on the number of visas for low-skilled workers that would be allowed under new legislation. The agreement was seen as removing a major obstacle to approval, but it still faces strong opposition from conservative quarters.

While immigrant activists said they expect a large crowd to converge at the Capitol on Wednesday, opponents said they are planning a small, low-key event nearby. Brad Botwin, director of Help Save Maryland, which opposes illegal immigration, said members will observe the rally but not compete with it.

“We know there has to be some compromise, but what we don’t want is for 11 million people to appear magically as citizens,” Botwin said. “The idea of a general amnesty is just wrong.”

Pro-immigrant activists say that they are not promoting amnesty, but rather an orderly system in which all illegal immigrants will have to wait in line, pay fines and back taxes, and learn English before applying for legal status.

Rufina Perera, 54, an office cleaner in the District, spent her lunch hour Thursday passing out leaflets at Union Station. For her, the chance to achieve legal status after 22 years in the United States would cap a long personal struggle that included fleeing war, being separated from her children for years, working nights for low wages and not being able to visit her relatives in El Salvador until last year.

“It still hurts,” Perera said as she waited in a crowded eatery to pass out fliers to several Latino workers serving up salads and burritos. “We have been here so long, and we have worked so hard to help our families. We are here to stay, and we need security. This is our time.”