“We came up with the money,” said Frank Sharry, founder and executive director of America’s Voice, a Washington-based group with close ties to the Obama White House. “We were just frustrated that nobody was doing anything, and Graham was under attack. We said, ‘Fine, we will put money in.’”

Sharry’s group, knowing an ad sponsored by a left-leaning advocacy group could hurt Graham, donated $60,000 to Republicans for Immigration Reform, a super PAC started by President George W. Bush‘s former Commerce secretary, Carlos Gutierrez, and GOP fundraiser Charlie Spies.

An unprecedented collection of political bedfellows has coalesced this year on the reform side of the immigration debate: liberal Latino organizations and Republican operatives, the Chamber of Commerce and labor unions, faith groups and high-tech companies. And as with the Sharry contribution, some left-leaning groups are financing Republican pro-immigration groups.

The result is a flood of money for advertising, lobbying and field organizing aimed at convincing Republicans in Congress to create a pathway to citizenship for the estimated 11 million people in the country illegally, authorize more temporary work visas and increase security on the border with Mexico.

During the first half of the year, reform backers outspent opponents in advertising by more than 3 to 1: $2.4 million to $700,000, according to Kantar Media’s Campaign Media Analysis Group. They also hired a battalion of lobbyists. In the second quarter, 527 businesses, advocacy groups and others reported lobbying on immigration, up from 389 in the first three months of the year, according to the Center for Responsive Politics.

Some of that spending is about to show up in targeted campaigns in House districts. Advocates are trying to keep up the pressure when members are home during the five-week August recess — or “Action August,” as President Obama called it last month. But the biggest spending is likely to come this fall, when the House is expected to take up a series of immigration bills.

“We will see a significant ramp-up of activities in August and September,” said Tom Snyder, who runs the campaign effort for the labor giant AFL-CIO. Some Republican House members have already started to soften their opposition to reform, he said, especially in districts with tens of thousands of union members. “What you are seeing is not an avalanche but a stream starting to trickle in our direction.”

The last time Congress took up the issue, in 2007, anti-immigration groups mounted a fierce grass-roots campaign and succeeded in defining the bill as “amnesty” for lawbreakers. This time, advocates have launched a preemptive strike.

“I’ve heard it said, it could be lost in August but not won in August,” said Spies, a lawyer who formed Republicans for Immigration Reform to provide “political cover.”

The AFL-CIO has spent $418,998 to run ads in at least six states and plans to spend more than $1 million in August and September targeting 40 Republicans in the House. The Service Employees International Union started a $200,000 radio campaign aimed at Republican congressmen in 10 districts with growing Latino populations, including four Californians: Jeff Denham (Atwater), Howard P. “Buck” McKeon (Santa Clarita), Gary G. Miller (Diamond Bar) and David Valadao (Hanford).

Two moderate Republican organizations also have participated. The American Action Network spent $182,085 on television ads, and Americans for a Conservative Direction spent $105,251 for ads in six states, according to Kantar Media.

FWD.us, an advocacy group founded by Facebook Chief Executive Mark Zuckerberg and funded by top tech executives, announced plans last week to spend more than $500,000 on ads featuring a young Chicago man who wants to become a Marine but can’t because he came to the country illegally as a 7-month-old.

Dan Stein, president of the Federation for American Immigration Reform, which opposes boosting immigration levels, said his side was badly outgunned. The tide of corporate money has moved the debate away from the promise of the poem on the Statue of Liberty to welcome the tired, the poor and the freedom-seekers, he said.

“Now, it’s give us your industrial and farm workers who are low-wage and poorly educated, or give us the technical talent from somebody else’s economy,” Stein said.

The immigration debate has drawn attention, and money, from a vast array of businesses: notably the tech industry, which wants more H-1B visas for highly trained foreign workers, but also other industries that rely heavily on immigrant labor, including agriculture and hotels. Since March, companies and trade groups signed up 76 more lobbying firms, according to the Sunlight Foundation and the Center for Responsive Politics.

Microsoft Corp. has been among the most active. In addition to its in-house lobbying operation, the company has paid lobbyists from 15 firms this year to press the case on Capitol Hill.

Fred Humphries, vice president for government affairs, said Microsoft supported reform efforts that would increase high-tech visas because U.S. colleges do not graduate enough computer scientists. “In the U.S. today, Microsoft has approximately 3,500 research and engineering jobs we can’t fill,” he said.

The business lobby’s influence on Republican lawmakers was on vivid display this spring. In March, Utah’s Republican senators, Orrin G. Hatch and Mike Lee, urged the Senate to slow down on immigration reform. That didn’t sit well at the Salt Lake City Chamber of Commerce, where many members had been agitating to increase high-tech visas. At a news conference, the chamber’s president threatened to mount a recall of Hatch and Lee.

Hatch soon changed course. He became a key player in the talks that led the Senate to approve a bipartisan bill authorizing up to 180,000 high-tech visas — nearly triple the current number.