[The Boston bombings] complicate an already complicated upcoming debate. Some people will use it as an issue to try to derail [immigration reform]. The bottom line is that there are a lot of people that want to do harm to this country. Some of them come from abroad, some of them live here and some of them have lived here for a while. It may or may not impede immigration reform, but at this point I think it’s important to be very careful not to conflate the issues.