Sen. Marco Rubio (R-Fla.) wants to strengthen requirements in a sweeping immigration bill that mandate that illegal immigrants learn English before earning permanent U.S. residency.

Under the current bill, immigrants would have to earn English proficiency or show they are enrolled in a language course. Rubio, a member of the bipartisan group that developed the legislation, plans to offer an amendment that would eliminate the second provision and require that undocumented immigrants be able to read, write and speak English before earning a green card.

The Senate bill allows undocumented immigrants to apply for a green card after 10 years and then apply for citizenship three years later.