The open letter to the Senate, which will be released Tuesday, marks the first large-scale attempt to halt the bill as it gains momentum with a key Senate committee vote expected this week.
Those signing the letter include influential conservative commentators – Erick Ericksen, Laura Ingraham, Mark Levin and Michele Malkin – as well as tea party leaders and talk radio hosts from around the country.
"No matter how well-intentioned, the Schumer-Rubio bill suffers from fundamental design flaws that make it unsalvageable,” said the letter, referring to Sens. Charles E. Schumer (D-N.Y.) and Marco Rubio (R-Fla.), key architects from the bipartisan group of eight senators that drafted the bill.
"Many of us support various parts of the legislation," the letter said, "but the overall package is so unsatisfactory that the Senate would do better to start over from scratch."
So far, opposition to the sweeping bill has been muted, and it is unclear whether this new effort will change the debate.
Republicans have declined to wage a full-throated attack on the bill, as happened in past immigration reform efforts, as the party hopes to improve its standing with Latino and minority voters.
Opponents signing the letter tapped into many emerging criticisms of the legislation, including its size – starting at 844 pages – which they call "bloated and unwieldy."
They also objected to the bill because, the letter said, it "legalizes millions of illegal immigrants before securing the borders, thus ensuring future illegal immigration" and "hurts American job seekers, especially those with less education."
The legislation includes a series of bipartisan compromises, including beefed-up border security in exchange for a 13-year path to citizenship for the estimated 11 million people who have entered the country illegally or overstayed visas. A low-skilled guest-worker system would be established to allow workers such as maids and landscapers to receive three-year visas, and employers would be required to verify the legal status of all workers.
The bill is making its way through the Senate Judiciary Committee and is expected to be passed this week to the full Senate for consideration, probably in early June.