"Late last week opponents of comprehensive immigration reform began to exploit the Boston Marathon bombing. I urge restraint in that regard," Leahy said in his opening statement at an immigration reform hearing on Monday.
Leahy said the immigration bill would improve national security.
"The bill before us would serve to strengthen our national security by allowing us to focus our border security and enforcement efforts against those who would do us harm," Leahy said. "But a nation as strong as ours can welcome the oppressed and persecuted without making compromises on our security. We are capable of vigilance in our pursuit of these values."
A number of lawmakers have said the bombing should be factored into crafting a new immigration reform law. At around the same time that Rubio published his tweet, Sen. Rand Paul (R-Ky.) released a letter to Senate Majority Leader Harry Reid (D-Nev.) and Senate Minority Leader Mitch McConnell (R-Ky.), arguing that the effort to overhaul the nation's immigration system should be paused until Congress fully investigates the Boston bombing and adds new protections into the legislation.
In the letter, Paul argued that "the Senate needs a thorough examination of the facts in Massachusetts to see if legislation is necessary to prevent a similar situation in the future."
—This story was updated at 12:21 p.m.