President Obama and Immigration Reform

In Las Vegas today, President Obama said it's good news that bipartisan groups in both houses of Congress are finally addressing immigration reform. The President endorsed the general principles laid down yesterday by a bipartisan group of US Senators, the most controversial aspect of which may be what's called the path to citizenship. Cautioning that the debate is sure to become emotional, he warned against letting it devolve into "us" versus "them." What's the likely impact of the immigration debate on the Republican Party, currently at an historic low point in California's political history?