Undocumented immigrants who came to the U.S. would have a 13-year process toward citizenship, but younger immigrants could apply to become citizens in as little as five years as part of the immigration proposal designed by the Senate's "Gang of 8" and released late Tuesday.

Reuters reported that young immigrants would be eligible for "green cards" within five years, and be able to apply for citizenship immediately after that. Though no age range was specified, this would suggest a path for immigrants who would have been covered by the failed DREAM Act of 2010 to become citizens.

Two members of the bipartisan group, Sen. John McCain (R-AZ) and Sen. Chuck Schumer (D-NY), said on Twitter that a public announcement of the proposal scheduled for Tuesday was postponed out of respect for the victims of the bombing in Boston on Monday.

They did, however, discuss the Border Security, Economic Opportunity, and Immigration Modernization Act of 2013, as the proposal is called, in a column for the Wall Street Journal posted Monday evening.

"This legislation is truly comprehensive," they said "It would provide a credible way for undocumented immigrants to apply for legalization and eventually citizenship—but only after specific, achievable steps have been taken, including securing our southern border with the deployment of unmanned aerial vehicles and other proven surveillance capabilities. We believe that Americans will accept a common-sense approach to the 11 million undocumented immigrants who are here now, and to prospective legal immigrants, provided that there will be no future waves of illegal immigration."

The citizenship program would be open to immigrants who came to the U.S. before Dec. 31, 2011. If signed into law, immigrants who would be able to apply for six-year "registered provisional immigrant" (RPI) visas within six months after it goes into effect. Applicants would require a clean criminal record and would have to pay a $500 fee and back taxes to be eligible. But once in the program, they would be eligible to work for any employer while being allowed to travel outside the U.S. The bill also requires all employers to use the "E-verify" system within five years.

After 10 years, visa holders who show regular employment and English-language proficiency would be eligible to apply for permanent legal residency, and apply for citizenship three years after that.

ABC News reported that the bill also calls for $4.5 billion to be used to boost security measures along the U.S.-Mexico border by adding unmanned drones and adding 3,500 agents to the Border Patrol.

Immigration rights advocates have criticized the group's emphasis on security, citing a record number of deportations by President Barack Obama's administration and a net-zero immigration level from Mexico. The head of the American Civil Liberties Union, Anthony D. Romero, reaffirmed those sentiments in a statement released Tuesday.

"The roadmap to citizenship should not exclude people based on minor crimes or people who can't afford hefty fines," Romero said. "The bill needlessly expands wasteful border spending at a time when border communities are safe, enforcement resources are at record levels, and prior benchmarks have been met."

McCain and Schumer defended the bill's security provisions in their column, saying it would ensure "that high-risk areas of the border meet specific metrics of control and surveillance, and provide the resources and technology the Border Patrol needs to improve how it detects and apprehends illegal entries."

Deported immigrants would also be eligible to petition to return to the U.S. if their children, parents or spouses are U.S. citizens or permanent residents. Other family members would able to apply for a separate visa program allowing them to live in the U.S. for up to 60 days a year.

["Immigration Protest Rally Against Arizona's New Law on May 1, 2010 in Los Angeles, California" Katrina Brown / Shutterstock.com" via Shutterstock]