A bipartisan Senate group has agreed on a sweeping legislative proposal that would represent the most ambitious overhaul of the U.S. immigration system in three decades. The Washington Post will be examining portions of the bill on Post Politics in a series of blog entries.

ANNAPOLIS, MD - MARCH 7: On Monday, Maryland immigrants and supporters rallied in Annapolis in support legislation in support os immigrant access to higher education and opposition to 29 anti-immigration bills. More than 1,500 were expected to attend. GustavoTorres, 49, director of CASA of Maryland, left and Maryland State Delegate Ana Sol Gutierrez participate in the rally. (Photo by Sarah L. Voisin/The Washington Post) GustavoTorres, 49, director of CASA of Maryland, left, with Maryland State Del. Ana Sol Gutierrez (D-Montgomery) on March 7. (Sarah L. Voisin/The Washington Post)

A key Washington area immigrant advocate, whose organization mainly represents the cause of undocumented Hispanic immigrants, welcomed the bipartisan Senate immigration bill Wednesday as an "historic achievement," but he expressed concern that some provisions could harm certain legal immigrants and that others did not go far enough to help illegal immigrants.

Gustavo Torres, executive director of the group CASA of Maryland, objected to the proposed cutoff date of Dec. 31, 2011, by which an illegal immigrant must have been present in the United States to apply for Registered Provisional Immigrant Status and begin a path to permanent residency and citizenship. Torres said that more than 400,000 people who entered the U.S. without authorization during 2012 would be immediately excluded from legalization and subject to deportation.

"This is very problematic for our people and our community," said Torres, noting that thousands of undocumented immigrants, including some who traveled to the U.S. illegally in 2012, may have families, jobs and longtime homes here. He complained that they would be "immediately undocumented as soon as President Obama signs the bill."

Torres also complained about the 13-year wait for citizenship that the bill requires of illegal immigrants who have obtained provisional status. He pointed out that many people from Mexico and other countries have lived in the United States for 20 and even 30 years, even though they are still undocumented. "To make them wait another 13 years is really unfair," he said.

However, he also expressed concerns about several items in the bill that would affect legal immigrants from other parts of the globe, and which he said would have no impact on illegal immigrants from Latin America. In particular, he objected to the proposal to scrap the so-called diversity visa lottery, in which foreigners from many countries may apply for an American green card.

Torres said this system was one of the few ways people from Africa and other poor regions have had any chance of immigrating. It was established in 1990 and offers 65,000 such visas each year to applicants from any country that has not had a large number of recent immigrants. The elimination of the diversity visa program was part of the Senate negotiations that included raising the number of work-related visas.

By the same token, the CASA official objected to the bill's proposal to emphasize visas for skilled workers, which it calls "merit-based" visas, over family-based immigration. The Senate bill, while speeding up the current waiting list for family-related visas, would eliminate 70,000 future green cards for some relatives, such as siblings and unmarried adult children, who may now be sponsored by a legal immigrant.

"We believe immigration should be family based, and that corporations should not have the power over who can come here and who cannot," Torres said. One of the key components of the bill is an increase in the number of skilled foreigners who can obtain work visas, a demand made by high-tech and scientific employers who say they cannot find enough American workers with special skills.