Sorry, just a quick second reply. I disagree that Congress is responding to the president's push on this issue. I believe they are responding to the massive street protests of the House bill, and the media attention those multi-city protests garnered. Say what you will about them, filling the streets of several major cities with protesters definitely works, and that's what sent this into crisis mode, in my view. regards, h.
I may be wrong, but I believe the Senate calendar scheduled debate on immigration for March, and that calendar was set in January. So the marches were timed to coincide with Senate consideration of the issue.