Then comes August, the month in which legislation dies. The last time the Senate passed a major immigration bill in 2006, House Republicans used the August recess to kill it by staging a series of hearings around the country that did nothing but rile up conservatives against it.

Let’s not forget the health care bill, which only passed after President Obama forced it through the Senate with Democratic votes using a parliamentary tactic that isn’t available on immigration. It was in August of 2009 that Sen. Chuck Grassley, R-Iowa, then the ranking member of the Finance Committee, definitively announced his opposition to the health care bill, ensuring that GOP senators would line up behind him. And at that time, Democrats controlled the House, which is how Obama pushed that bill over the finish line.

When lawmakers return to the Capitol in September, they will be facing another financial crisis as they debate raising the country’s debt ceiling. The four- to six-week countdown toward extreme limitations on government payments to Social Security or military operations will do two things: It will suck all the life out of any deliberative legislative effort, immigration included, and it will polarize the political parties. It will be far from fertile ground for the biggest immigration overhaul in 30 years.

Proponents of the Senate’s immigration package are hoping that a strong vote this week among senators will push the more reluctant House Republicans to act, if only to get the emotional issue out of the way. “We know there’s going to be hard-line opponents. We know there’s a number of people, [Rep.] Paul Ryan, [D-Wis.], and others, who are in favor of this and will be pitching it to their colleagues.… That’s going to be the group that’s interesting to watch,” said America’s Voice Executive Director Frank Sharry.