A much-needed immigration bill has already become part of the aftershock of the Boston bombings. Democratic Senator Charles Schumer of New York, one of the bill’s sponsors, accused some of his colleagues this week of using the bombings as an excuse to delay, or stop, the proposal from moving forward.

Whether or not some senators are exploiting another tragedy for political purposes, cooler heads must prevail. With emotions running high, this is no time for political pandering or the kind of xenophobia that typically follows a calamity perpetuated by anyone except a natural-born citizen.

To be sure, overhauling the nation’s immigration system is too important, and complicated, to rush through. But that’s all the more reason to start the debate now. A path to citizenship for the nation’s 11 million illegal immigrants has absolutely nothing to do with any terrorism attack ever perpetuated on American soil.

In the case of last week’s bombings of the Boston Marathon that killed three and injured more than 180, the two suspects are foreign born. Dzhokhar and Tamerlan Tsarnaev were members of an ethnic Chechen family that received asylum in 2002.

But the brothers were here legally. Dzhokhar, now in police custody, is a naturalized citizen. Tamerlan, whom police killed in a shootout, had a green card and was applying for citizenship.

In fact, virtually all of the major terrorist attacks on U.S. soil over the past 40 years were committed by natural-born citizens — Oklahoma City, for example — or people who entered the country legally. Even most of the 9/11 hijackers obeyed the nation’s immigration laws.

Tougher background checks for people applying for visas might make sense, but the nation’s flawed immigration system is not the cause of terrorism. Those failings, however, have left millions of undocumented immigrants in limbo, while they perform some of the nation’s hardest and dirtiest work.

They have also penalized foreign-born young people who were brought here illegally but who are now Americans in every way but name. And they have failed to adequately deal with the tiny number of illegal immigrants who pose a risk to public safety.

Even during a time of calamity — especially during such times — Congress must continue to do the people’s work in a rational and responsible manner. That means moving forward with long-delayed immigration reforms.