"They said that in focusing first on border security, Mr. Obama might be giving up his best leverage for winning approval of broader but more politically contentious steps to address the status of the millions of immigrants already in the United States illegally, and the needs of employers who rely on their labor." from The New York Times
The amnesty-advocates really don't get it. The president isn't supposed to use the intensity in which he controls our border as "leverage" to extract concessions for people who have violated the law in the process of coming to (or remaining in) the United States. As the chief law enforcer of the land, the president is supposed to secure our borders because it is the law and sending more patrol officers to the border is a part of his constitutional mandate to protect this country from those who would enter the country illegally, for whatever reason.
Mr. Obama really has no legal choice in the matter. Whether he gets the amnesty bill that he want or not, the president has to secure our borders. He cannot threaten to withhold enforcement of laws he doesn't like to extract concessions for something that he wants and still claim (with any legitimacy) that he is impartially upholding the laws of the land.