Lawmakers raised questions Monday about provisions in the proposed immigration overhaul which could create a fast track to legal status for some agriculture workers — as tempers flared over the separate issue of the Boston bombing and whether it should influence the content of this bill.

Senate Democrats and Republicans, debating the bill at the second hearing held since its introduction, differed over whether illegal immigrants working on U.S. farms should be eligible for a new so-called blue card, which would allow them permanent residence after five years.

Non-farmer workers in the United State illegally would have to wait about twice as long to achieve that status.