A coalition of high-profile conservatives and tea party activists has signed a letter urging members of Congress to oppose a bipartisan Senate immigration bill, an attempt to increase public pressure just days before it faces an initial committee vote.

In the letter, the group writes that the bill, developed by four Democrats and four Republicans, would allow illegal immigrants to gain citizenship before securing the U.S. borders, bankrupt the entitlement system and favor foreigners over Americans in low-skilled jobs.

“Many of us support various parts of the legislation,” the group wrote, “but the overall package is so unsatisfactory that the Senate would do better to start over from scratch.”

Among those who signed the letter are radio hosts Laura Ingraham, Monica Crowley and Mark Levin, author Michelle Malkin, activist Phyllis Schlafly, former congressman Allen West, former Republican presidential candidate Gary Bauer, National Review editor Rich Lowry and Jenny Beth Martin, co-founder of the Tea Party Patriots.

The document was distributed Monday night by the office of Sen. Jeff Sessions (R-Ala.), one of the most outspoken opponents of the bill. Sessions, a member of the Judiciary Committee, has offered dozens of amendments aimed at altering or eliminating key provisions, though most of them have failed over four days of committee hearings that continue Tuesday.

Supporters of the legislation say it would invest billions of dollars in new border control measures and set tight limits on the number of foreign workers in fields such as construction so that Americans are not disadvantaged.

In all, about 150 people and organizations signed the letter, which compares the comprehensive immigration bill to the Obama administration’s sweeping health care reform bill in 2010.

The bill is “bloated and unwieldy along the lines of Obamacare or Dodd-Frank,” the coalition writes. It “cedes excessive control over immigration law to an administration that has repeatedly proven itself to be untrustworthy, even duplicitous.”

The public pressure is unlikely to stall the bill in committee, where Democrats outnumber Republicans, and two of the GOP members are members of the bipartisan group that authored the legislation. Judiciary Committee Chairman Patrick J. Leahy (D-Vt.) has said he hopes to complete the amendment process by the end of this week in preparation for a committee vote, likely sending the bill to the full Senate floor next month.

President Obama, who has made immigration reform his top second-term priority, will meet Tuesday with young undocumented immigrants – known as Dreamers – whose deportation cases have been deferred by his administration under a presidential action he ordered during the campaign last summer.