Leaders in the US Senate said Monday that a final vote on the immigration reform agreement reached last week would be delayed until June due to opposition from both sides in Congress. Some Republican senators have derided the immigration reform proposal as amounting to "amnesty" for up to 12 million undocumented immigrants currently in the United States and would like to see a tougher proposal on undocumented immigrants seeking legal status, by either increasing fines or requiring the immigrants to return to their native country before applying for citizenship. Democratic objections to the proposal have focused on the restrictions on the right of legal immigrants to be joined by their families and its preference for high-tech workers and employability over familial ties. Lawmakers from both aisles have also criticized the temporary worker visa program, which will annually provide at least 400,000 guest worker visas, as too large.

If approved, the Comprehensive Immigration Reform Act of 2007, characterized by President Bush as "secure, productive, orderly, and fair", will give undocumented immigrants the opportunity to obtain a probationary card allowing them to live and work legally in the United States, but which would not place them on the road to permanent residency or citizenship. Critics of the measure say that it threatens to create a permanent underclass of low-income low-skill jobs that are denied the opportunity to establish roots in the United States. Senate leaders had initially hoped to hold a final vote on the legislation before Memorial Day, but Senate Majority Leader Harry Reid (D-NV) said Monday that attempting to finish the bill by the end of the week would not be in the Senate's best interests.