I'm not sure it was a good idea to oppose this. It's essentially the republicans saying "We don't want to let any more people in the country, but of the people we are letting in, we prefer the highly educated". In a time when countries like China are graduating 50k engineers a year, you'd think being choosy about who you let into the country would make sense. And I don't see how signing this hurts the Democrats' long term plan for immigration reform. I assume that involves bringing more people into the country, so ok, bring more in later when the economy recovers. Not compromising on this bill setting a bad precedence for any compromise that may happen in the future.
It takes away the Republicans' opportunity to claim they already addressed immigration reform and that any further action is the President "going too far."
The Republicans are between a rock and a hard place politically on immigration. Latinos are the fastest-growing demographic in the country, and Republican hostility toward immigration reform is starting to cost them in elections. e.g., Obama pummeled Romney among Latino voters in Florida by an over 2-to-1 margin. [1]
The Republicans have essentially painted themselves into a corner on the issue and are in a no-win situation. If they continue to aggressively oppose immigration reform, it's going to hurt them with an increasingly-important demographic. If they concede and compromise, Obama and the Democrats get to claim themselves as the champions of immigration reform, which still hurts the Republicans, though to a lesser degree.
Obama knows he has major leverage over the Republicans on this issue; it doesn't make political sense to make concessions they can paint as wins if it's not the reform he's actually after.
It really makes sense from a negotiation standpoint. It's generally expected that immigration reform will be a banner issue for Obama this term, and this bill was likely an attempt by the Republicans to get out ahead of the issue before more sweeping legislation is introduced.
By refusing to cooperate on this bill, it signals that the White House and the Senate are unwilling to let the Republicans pick and choose on reform, meaning that the issue is going to be addressed in the more comprehensive manner that the Democrats feel is necessary.
