They are taking a leaf out of Obama's book. By now, it should be clear to everyone - with the healthcare debate and all- how difficult it is to remove or reverse a law.
It is very unlikely that Republicans will be able to eliminate the healthcare mandate. Instead they have to go on the defensive, and try to defund it, delay it, etc.
There's only a brief window of opportunity to eliminate these before the mechanisms are in place for them to be used. Once the wheel gets rolling and people have been hired, money has been allocated, processes are in place; it becomes very difficult to make new laws because they require new lawmakers.

And this is how the Obama administration is trying to con immigration reform parties: New laws require new lawmakers in Congress, an so we are supposed to remain in permanent limbo until the next election. There will always be a "next election".

In the meantime, the Reps are going batshit crazy at full speed to create as many anti-immigration laws as TIME will permit them, and force the administration and the Democrats that do care about immigrants, to spend energy, money and their legislative TIME trying to stop them, instead of writing their own legislation.