STEVE INSKEEP, HOST:
A bipartisan immigration bill in the U.S. Senate contains a prerequisite. Before millions of people in the U.S. without documents have a chance at visas and eventual citizenship, the borders must be secured. So what qualifies as secure?
Here's NPR's David Welna.
DAVID WELNA, BYLINE: For years, Republican lawmakers have insisted that before anything can be done for the millions of people in the country unlawfully, the land borders over which most of them entered must be brought under control. Asked about the Gang of Eight's immigration bill, here's what Texas Republican Senator John Cornyn told Fox News.
SENATOR JOHN CORNYN: I believe border security is absolutely critical to this picture and so much of it is regaining the public's confidence that the federal government is actually doing its job.
WELNA: And Iowa House Republican Steve King says he doesn't even want to see an immigration bill until there's more order on the border.
REPRESENTATIVE STEVE KING: My position would be if you're serious about securing a border, go secure it and then come back and talk to us.
WELNA: On Sunday, Florida Republican Senator Marco Rubio sought to quell this issue when he talked up the immigration bill on seven different TV networks, one of them ABC.
SENATOR MARCO RUBIO: We are going to get the toughest enforcement measures in the history of this country. We are going to secure the border to the extent that's possible.
WELNA: But what Rubio did not say was how such border security might be measured. Up until two years ago, the Department of Homeland Security used a metric known as Operational Control, the number of miles along the borders where the Border Patrol could not just detect, but also intercept illegal intruders. But that's no longer being used, according to Michigan House Republican Candice Miller who chairs the committee that oversees U.S. borders.
REPRESENTATIVE CANDICE MILLER: The Department of Homeland Security for the last two years has told us that they are not going to use the term Operational Control because it's antiquated and instead they're going to have a new system of measuring it called the Border Control Index, the BCI, but a month ago, they just told us, well, we also don't think that's very effective so now we have nothing.
WELNA: And that's caused considerable annoyance among those trying to run up support for the Senate immigration bill. Arizona Republican John McCain is a member of the Gang of Eight. He vented his frustration over the lack of clear security measurements last week at a Senate Homeland Security meeting.
SENATOR JOHN MCCAIN: We don't have the metrics and we need the metrics and we need them very badly if we're going to consider overall immigration reform.
WELNA: McCain addressed his remarks to a witness at the hearing, U.S. Border Patrol Chief, Michael Fisher.
MCCAIN: I hope you can establish those metrics and I'd be more than happy to hear from the government accountability office that you have done so. As short a time ago as last week when I talked to them, that hasn't happened.
CHIEF MICHAEL FISHER: Well, it is in the final stages of development, Senator, I can tell you that.
WELNA: And yet, at about the same time, Fisher's boss, Homeland Security Secretary Janet Napolitano was telling a House panel that while it may be tempting to draw an arbitrary number out of the air, such a magical number is not what's needed.
SECRETARY JANET NAPOLITANO: I think some kind of false border security number doesn't really get us anything in terms of maximizing border safety.
WELNA: In fact, for Napolitano who is to testify later this week on the new immigration bill, the insistence on measuring border security could prove a stalking horse for those opposed to an immigration overhaul.
NAPOLITANO: For those who are seeking immigration reform, the suspicion, quite frankly, is that some sort of false border security metric, if you can ever decide on one Holy Grail, is actually a reason never to get to reform of the underlying system.
WELNA: To Michigan House Republican Miller, that sounds like one more excuse.
MILLER: I don't think we're searching for the Holy Grail, as they say. It is not rocket scientry(ph). But to just say that, well, it's tough, you know, hard to do, so therefore we can't do it, is not the correct answer.
WELNA: Miller says she's actually open to an immigration overhaul. It would be too bad, she adds, if the department responsible for securing the border proved a stumbling block to making that happen. David Welna, NPR News, the Capitol.
INSKEEP: This is NPR News.
(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.