By Kathy Kiely, USA TODAY

WASHINGTON — As backers of a plan to overhaul the nation's immigration laws push for Senate passage by the end of the week, their challenge will be to fend off a series of amendments that could torpedo the delicately balanced compromise.
"It's easy for this coalition to become frayed," Sen. Dianne Feinstein, D-Calif., said of the bipartisan group of senators who crafted the deal with White House support.

The legislation, which the Senate will resume debating today, would beef up security along U.S. borders and expand opportunities for foreigners to work in the USA. It would also change the criteria for admitting immigrants — now based largely on family ties — to give more weight to job skills, and grant an estimated 12 million people living illegally in the country a chance to become citizens.

Members of President Bush's Cabinet said they made headway during last week's congressional recess selling businesses and other groups on the need for the so-called "grand bargain."

"There's great momentum among these groups," said Commerce Secretary Carlos Gutierrez, who estimated that he spoke to nearly 300 representatives of business and civic organizations across the ideological spectrum. "A week ago they were in a different place."

Opponents promise to push back. "We have seen a lot of activism and we anticipate a lot next week," said Caroline Espinosa of NumbersUSA, a group that wants to reduce immigration. Because the deal is drawing criticism from the Democratic left and Republican right, "we see a great possibility they will not pass it," Espinosa said.

Among the amendments likely to be offered to change the bill:

• Sens. Robert Menendez, D-N.J., and Barack Obama, D-Ill., will seek to end the merit-based point system for immigration after five years. The bill creates a point system to determine an immigrant's ability to succeed in the job market, increasing the percentage of future immigrants based on job skills rather than family ties.

• Menendez and Sen. Chris Dodd, D-Conn., want to increase the number of immigration slots for parents of U.S. citizens.

• Sen. Jeff Sessions, R-Ala., will propose a measure to deny tax credits for the working poor to foreign guest workers and to illegal immigrants who are in the process of earning legal status.

• Sen. Kay Bailey Hutchison, R-Texas, will seek to prevent illegal immigrants who earn legal status under the bill from claiming Social Security benefits for the time they worked illegally.

Members of the bipartisan coalition supporting the bill insist they will continue to oppose amendments that could unravel the deal, even if they favor them personally. "We have voted against our personal preference because the totality of the bill is so important," said Sen. Arlen Specter, R-Pa.

It has been more than 20 years since Congress tackled such a sweeping overhaul of the rules and regulations that govern who may become an American.

"This is an enormously emotional and contentious issue," said Sen. John Cornyn, R-Texas.