The Senate is attempting to pass this. What are the chances that it'll pass the House?

This seems unlikely to be successfully blocked in the Senate (though it's still worth trying; different arguments might work with different senators, talk to yours). But it would help to rapidly talk to representatives to ensure that they vote "no" on the overall act.

Of course, the whole thing should be a "no" with or without this amendment; the Patriot Act should just die unrenewed. But if you can't convince your representative to vote no no matter what, try to convince them to vote no specifically if this amendment or anything like it is in the bill.