Boston bombing suspects Dzhokhar and Tamerlan Tsarnaev were living in the United States legally – and some say the brothers are the perfect example of why the U.S. is not prepared to welcome more immigrants.

“The failure to control immigration and the excessive volume of immigration poses a serious threat to homeland security,” said Ira Mehlman, a spokesman for the Federation for American Immigration Reform, which opposes the immigration reform bill introduced to the Senate last week.

Mehlman said the U.S. needs an immigration policy that admits people in manageable numbers, so that it can do “due diligence” on each and every person granted residence.

“Nobody could have been more out of the shadows than the Tsarnaev brothers … We got warnings from the Russian government that one posed a threat, and we still did nothing about it!” said Mehlman.

But some in the business community argue immigration reform will fill in gaping holes in the labor market, giving the economy a necessary push in the right direction; and the tragic alleged terror attack during the Boston Marathon should not slow its passage.

“It forces the imperative to fix our broken system, so that entrepreneurs can start businesses here and stay here,” said Engine Advocacy cofounder Mike McGeary in reference to the proposed legislation in an interview with FOXBusiness.com last week.

McGeary said the lottery for high-skilled worker visas has driven U.S. tech companies to settle in other countries such as Canada, which unveiled a recent startup visa for entrepreneurs.

Reform advocates also say there’s a need for visas for unskilled laborers – especially in states where the economy depends on agriculture or construction.

Arizona Employers for Immigration Reform executive director Todd Landfried said detractors who try to use the Boston bombing to derail immigration reform are missing the broader point of why we need immigration reform, in order to help the economy. Timothy McVeigh and Ted Kaczynski, he said, are examples proving that immigrants aren’t the only residents who pose a threat to American safety.  

“This is intended to be a distraction by people who don’t want to see the laws change,” said Landfried.

Senators Debate the Threat
At a hearing last week, Sen. Chuck Grassley,  (R-Iowa), said the Boston bombings led him to question the “gaps and loopholes” in our current system.

"How can we beef up security checks on people who wish to enter the U.S.? How do we ensure that people who wish to do us harm are not eligible for benefits under the immigration laws, including this new bill before us?" Grassley said.

But on Monday, Sen. Patrick Leahy, (D-Vermont), took issue with that line of thinking.

“Late last week opponents of comprehensive immigration reform began to exploit the Boston Marathon bombing.  I urge restraint in that regard.  Refugees and asylum seekers have enriched the fabric of this country from our founding,” Sen. Leahy said.

“Let no one be so cruel as to try to use the heinous acts of two young men last week to derail the dreams and futures of millions of hardworking people … A nation as strong as ours can welcome the oppressed and persecuted without making compromises on our security,” said Sen. Leahy.

Follow Gabrielle Karol on Twitter @GabrielleKarol