Assume the plot is Real. OK. Give Me Liberty or Give Me Death. Yes, people die protecting democratic institutions. Yes The Government would be committing political suicide if it did not seek to protect the general public, but unless it can demonstrate either in "hot pursuit" or via "oath or affirmation" (aka warrant) that the suspect is in the process of deploying such a bomb, then The Government has no right to search, seize, or otherwise control the suspect, his property or to limit his freedom.
If tens of thousands die, then it is a horrific crime. And retaliation against the sponsoring nation will be swift and supported by the world over (in fact that retaliation is part of what puts the limits on this sort of terrorism). Just as world opinion supported the invasion of Afghanistan, the same would be true here. But democracy and the commitment to democracy, demands that we all be willing to die for that commitment. Remember that the signers of the Declaration of Independence committed their "Lives, ...Fortunes, and...Sacred Honor" to the defense of democratic principles. And the immediate threat to them was far more real than anything leveled at Padilla or any other terrorist plot that has been allegedly interdicted.
If enforcing due process is at cross purposes with combatting terrorism then so be it.
Those who would sacrifice any of our precious liberties for a temporary measure of security, deserve neither liberty nor security - Benjamin Franklin.
If the law needs changing, you need to change it within the limits of the US Constitution. While the deaths of thousands, even millions would be horrific, the consequences of not having the courage to risk that is to surrender what shreds of democracy we have.
Remember that the USSR has a very fine sounding Constitution. :
Article 50:In accordance with the interests of the people and in order to strengthen and develop the socialist system, citizens of the USSR are guaranteed freedom of speech, of the press, and of assembly, meetings, street processions and demonstrations.
But of course we all know that in the name of "national security" the USSR Government trampled these rights for millions, including my grandfather who was tortured to death because of a book he wrote
I for one, hold the US to a higher standard than that of the USSR.