A number of conservative opponents of immigration reform, including Ann Coulter and Rep. Steve King (R-IA), suggested last week that a bill should be delayed or derailed in light of the bombing. In addition to Leahy, Sen. Marco Rubio's (R-FL) office pushed back against these efforts last week.
Leahy warned in particular that the discovery that the two suspects in the attack, Dzhokar Tsarnaev and Tamerlan Tsarnaev, were immigrants with roots in wartorn Chechnya should not lead Americans to suspect other immigrants who arrived as refugees.
"Whether it is the Hmong in Minnesota, Vietnamese Americans in California, Virginia and Texas, Cuban-Americans in Florida, New Jersey, or Iraqis in Utah, our history is full of these stories of salvation," he said. "Let no one be so cruel as to try to use the heinous acts of the young men last week to derail the dreams and futures of millions of hard-working people."
He added that the bill could strengthen the nation's defenses against terrorism by "allowing us to focus our security and enforcement efforts against those who would do us harm" instead of on tracking and deporting the nation's 11 million undocumented immigrants.
"A nation as strong as ours can welcome the oppressed and persecuted without compromising our security," he said.
Sen. Chuck Grassley (R-IA), who brought up the Boston attacks in Friday's hearing, disagreed with Leahy's assessment that it was exploitive to tie the investigation to immigration reform.
"I want you to take note of the fact that when you proposed gun legislation I did not accuse you of using the [Newtown] killings as an excuse," he said. "And I do not hear any criticism of people when there are 14 people killed in West, Texas and demanding to take advantage of that tragedy to warn about more government action to make sure that fertilizer factories are safe. I think we are taking advantage of an opportunity when once in 25 years we deal with immigration to make sure that every base is covered."
Update: Later in the hearing, Sens. Chuck Schumer (D-NY) criticized "those who point to the terrible tragedy in Boston as, I would say, an excuse for not doing a bill or delaying it many months," prompting an outraged Sen. Chuck Grassley (R-IA) to interrupt, shouting "I never said that!" Schumer later clarified that he was not referring to Grassley personally.
Video of the tense exchange below: