The political impact of the issue aside, there was no doubt that the Senate bill was on track for passage by Thursday or Friday.
Supporters posted 67 votes or more on each of three procedural tests Wednesday, far more than the 60 needed to prevail. More than a dozen Republicans sided with Democrats on each, assuring bipartisan support that the bill's backers hope will change minds in the House.
At its core, the legislation includes numerous steps to prevent future illegal immigration, while at the same time it offers a chance at citizenship for millions living in the country illegally.
It provides for 20,000 new Border Patrol agents, requires the completion of 700 miles of fencing and requires an array of high-tech devices be deployed to secure the border with Mexico.
Businesses would be required to check on the legal status of prospective employees. The government would be ordered to install a high-tech system to check on the comings and goings of foreigners at selected international airport in the United States.
Other provisions would expand the number of visas for highly skilled workers relied upon by the technology industry. A separate program would be established for lower-skilled workers, and farm workers would be admitted under a temporary program.
Some farm workers who are in the country illegally can qualify for a green card, which bestows permanent residency status, in five years.
Many of the bill's supporters also cheered a ruling from the Supreme Court that said married gay couples are entitled to the same federal benefits as heterosexual couples. They said the decision would probably allow gay married citizens or permanent residents to sponsor their spouses for U.S. residency.
The basic legislation was drafted by four Democrats and four Republicans who met privately for months to produce a rare bipartisan compromise in a polarized Senate. They fended off unwanted changes in the Senate Judiciary Committee, and then were involved in negotiations with Republican Sens. John Hoeven of North Dakota and Bob Corker of Tennessee on a package of tougher border security provisions that swelled support among Republicans.
Across the Capitol, an attempt at a bipartisan deal faltered, and majority Republicans began moving ahead on legislation tailored to the wishes of conservatives and vehemently opposed by Democrats.
The House Judiciary Committee already has approved two measures and was at work on a third during the day as it followed a piecemeal path rather than the all-in-one approach of the Senate.
The House bill under consideration Wednesday would require businesses to check on the legal status of employees within two years, as compared with four in the Senate measure.
One of the bills approved earlier makes it a new crime to remain in the country without legal status. It also allows state and local governments to enforce federal immigration laws, an attempt to apprehend more immigrants living in the United States illegally. It encourages those living in the United States unlawfully to depart voluntarily.
The second bill that cleared last week deals with farm workers who come to the United States temporarily with government permission. Unlike the Senate legislation, it offers no pathway to citizenship.
With attention beginning to shift to the House, Rep. John Fleming, R-La., said House Speaker John Boehner, R-Ohio, had assured the rank and file they will vote on bills being written on their side of the Capitol. "We are not going to take up the Senate bill," Fleming said, quoting the speaker.
Internal divisions among Republicans, combined with overwhelming opposition among Democrats, recently sent a farm bill down to defeat in the House, and it is unclear if the GOP will be able to command a majority for its own approach to immigration legislation.
At the same time, rules generally guarantee Democrats a chance to have the full House vote on its own alternatives, and it is unclear whether they might seek the vote on the Senate bill that Republicans hope to avoid.
For now, supporters of the Senate bill contented themselves with urging the House to change their minds.
"A permanent, common-sense solution to our dysfunctional system is really in sight," said Senate Majority Leader Harry Reid, D-Nev. "It is my hope that our colleagues in the House will follow the Senate's lead and work to pass bipartisan reform and do it now."
Outnumbered critics said the measure fell far short of the claims made by its backers.
"It continues to promote false promises that the border would be truly secure," said Sen. Charles Grassley, R-Iowa.
A short while later, Rubio, without mentioning anyone by name, stood at his desk to slam opponents of the Senate bill for what he said are false accusations.
He said it is not true, for example, that the administration can ignore the requirements for border protection or that future Congress' can cancel funding or that it creates a taxpayer subsidy for people to buy a car or a scooter.
Nor are critics correct to claim a new 1,100-page bill was recently introduced that no one has read, he said.
"This is the exact same bill that's been publicly available for 10 weeks, he said, with the exception of about 120 pages that require tougher border security.
A look at the immigration overhaul bill now before the Senate, as amended to include new provisions on border security the Senate agreed to Wednesday.
The bill sets out a series of requirements that must be achieved over 10 years before anyone here illegally can obtain a permanent resident green card. These include:
(1) Roughly doubling the number of Border Patrol agents stationed along the U.S.-Mexico border, to at least 38,405.
(2) Completing 700 miles of pedestrian fencing along the border, which would require approximately 350 new miles of fencing.
(3) Installing a host of new security measures and technologies in specified locations along the border, including specific numbers of surveillance towers, camera systems, ground sensors, radiation detectors, mobile surveillance systems, drones, helicopters, airborne radar systems, planes and ships.
(4) Implementing a system for all employers to verify electronically their workers' legal status.
(5) Setting up a new electronic system to track people leaving the nation's airports and seaports.
The border security improvements are designed to achieve 100 percent surveillance of the border with Mexico and ensure that 90 percent of would-be crossers are caught or turned back.
If the goals of a 90 percent effectiveness rate and continuous surveillance on the border are not met within five years, a Southern Border Security Commission made up of border-state governors and others would determine how to achieve them.
Border security spending in the bill totals around $46 billion.
Path to citizenship
The estimated 11 million people living in the U.S. illegally could obtain "registered provisional immigrant status" six months after enactment of the bill as long as:
(1) The Homeland Security Department has developed border security and fencing plans, per the specifications set out in the bill.
(2) They arrived in the U.S. prior to Dec. 31, 2011, and maintained continuous physical presence since then.
(3) They do not have a felony conviction or three or more misdemeanors.
(4) They pay a $500 fine.
People in provisional legal status could work and travel in the U.S. but would not be eligible for most federal benefits, including health care and welfare.
The provisional legal status lasts six years and is renewable for another six years for $500.
People deported for noncriminal reasons can apply to re-enter in provisional status if they have a spouse or child who is a U.S. citizen or permanent resident, or if they had been brought to the U.S. as a child.
After 10 years in provisional status, immigrants can seek a green card and lawful permanent resident status if they are current on their taxes and pay a $1,000 fine, have maintained continuous physical presence in the U.S., meet work requirements and learn English. Also the border triggers must have been met, and all people waiting to immigrate through the legal system as of the date of enactment of the legislation must have been dealt with.
People brought to the country as youths would be able to get green cards in five years, and citizenship immediately thereafter.
The cap on the H-1B visa program for high-skilled workers would be immediately raised from 65,000 a year to 110,000 a year, with 25,000 more set aside for people with advanced degrees in science, technology, engineering or math from a U.S. school. The cap could go as high as 180,000 a year depending on demand.
New protections would crack down on companies that use H-1B visas to train workers in the U.S. only to ship them back overseas.
Immigrants with certain extraordinary abilities, such as professors, researchers, multinational executives and athletes, would be exempted from existing green-card limits. So would graduates of U.S. universities with job offers and degrees in science, technology, engineering or math.
A startup visa would be made available to foreign entrepreneurs seeking to come to the U.S. to start a company.
A new merit visa, for a maximum of 250,000 people a year, would award points to prospective immigrants based on their education, employment, length of residence in the U.S. and other considerations. Those with the most points would earn the visas.
The bill would eliminate the government's Diversity Visa Lottery Program, which randomly awards 55,000 visas to immigrants from countries with historically low rates of immigration to the United States, so that more visas can be awarded for employment and merit ties.
A new W visa would allow up to 200,000 low-skilled workers a year into the country for jobs in construction, long-term care, hospitality and other industries.
A new agriculture worker visa program would be established to replace the existing program. Agriculture workers already here illegally, who've worked in the industry at least two years, could qualify in another five years for green cards if they stay in the industry.
Under current law, U.S. citizens can sponsor spouses, children and siblings to come to the U.S., with limits on some categories. The bill would bar citizens from sponsoring their siblings and would allow them to sponsor married sons and daughters only if those children are under age 31.
Legal permanent residents can currently sponsor spouses and children, but the numbers are limited. The bill eliminates that limit.
Within four years, all employers must implement E-Verify, a program to verify electronically their workers' legal status. As part of that, noncitizens would be required to show photo ID that must match with a photo in the E-Verify system.