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.