While Congress debates legalizing about 11 million immigrants living in the U.S. illegally, immigration advocates are pushing plans they say will open the asylum process for thousands more people who flee persecution in their home countries.

The Senate version of the immigration bill does away with a one-year filing deadline that Congress enacted in the 1990s to reduce fraud and that advocates say has prevented many legitimate asylum seekers from applying to the program.

The April revelation that the two brothers accused of carrying out the deadly Boston bombings arrived in the U.S. through the asylum system has concerned some lawmakers.

Homeland Security Secretary Janet Napolitano has said that nothing in the bill would weaken asylum procedures.