(CNN) – The border with Mexico must be secure.
This requirement is the cornerstone of an immigration reform bill a bipartisan group of senators are to file on Capitol Hill Tuesday. There will be no path to legal residency for migrants without it.
CNN: Terror at Boston Marathon: 3 dead, 144 wounded as witnesses describe horror
It was a gruesome end to what should have been a celebration of triumph. One man's legs were instantly blown off, yet he kept trying to stand up. Exhausted marathoners had to muscle the energy to flee the bloody scene. And more than 140 people remain hospitalized, some in critical condition. As authorities try to figure out who triggered the deadly bombings Monday at the Boston Marathon, which killed an 8-year-old boy and two others, many are at a loss to explain why anyone would target the annual event that celebrates thousands of runners from around the world.
ALSO SEE: CNN: What we know about the terror attack, aftermath at the Boston Marathon
ALSO SEE: CNN: Obama vows justice for Boston blasts
ALSO SEE: CNN: FBI to take lead in investigating Boston Marathon bombings
WATCH: VIDEO – CNN's Susan Candiotti delivers the latest on the FBI's investigation into the twin explosions at the Boston Marathon.