From the Washington Examiner, via Mark Krikorian on Twitter:

"Alabama members would have trouble explaining to their constituents why they broke with [Sessions] on immigration" http://t.co/qUd7vI4sKd

— Mark Krikorian (@MarkSKrikorian) August 1, 2014

More from the article:

A number of sources on Capitol Hill say lobbying by Alabama Sen. Jeff Sessions helped sway that state's House delegation against the bill, leading to the collapse.

After a frantic Thursday afternoon, House leaders said the chamber will meet Friday morning, when they hope to hold a vote and shepherd through a bill dealing with the influx of unaccompanied minors coming across the southern border.

Even if the bill passes then, the damage has been done to House leaders, who had to pull the bill they were pushing at the last minute — giving new Majority Whip Steve Scalise a headache on his first day on the job.

The push began at 9:45 a.m. Thursday, when Cruz and Sessions met to talk immigration strategy, according to a source close to Cruz.

Rep. Mike Rogers, an Alabama Republican, said Sessions then worked effectively to persuade the Alabama delegation to oppose the package. When asked how influential Sessions was on the delegation’s votes, Rogers said: “very.”

“He’s very respected and very knowledgable about this issue,” he said, noting that Alabama members would have trouble explaining to their constituents why they broke with the senator on immigration.

Aides said that Sessions’ behind-the-scenes and public opposition to the package played an outsize role in its failure.

“If you think this had more to do with Sessions than Cruz, I could say absolutely, there’s no doubt about it,” said one congressional aide.

Numerous other aides echoed that sentiment. One senior House Republican aide said that the senator’s messaging prowess played a significant part in hampering efforts to secure support for the package. [Links in original.]

The Alabama Congressional Delegation has six Republicans in the House of Representatives.

Ted Cruz deserves some credit (see Ted Cruz — Third Party Whip)  but while he's a conservative, and something of a populist, he's not likely to ever be as reliable on immigration as Jeff Sessions. (Which is one reason why it's unfortunate that we're more likely to see a President Cruz than a President Sessions.)