The explanation for this peculiar procedure is fear that the House would "blue slip" the bill. Let's refer to the U.S. Constitution. Article 1, Section 7 gives sole power to the House to originate all bills for raising revenue. This is known as the Origination Clause. If the Senate oversteps and includes a provision to raise some revenue (which the Gang of 8's Senate amnesty bill does), the House can reject the bill and send it back to the Senate for correction. This is known as the "blue slip" procedure.
Representative Paul Ryan has developed a devious plan to circumvent this constitutional rule. The plan is for the House to pass five or six bills on various aspects of amnesty, and then use that bunch of bills to call for a conference committee with the Senate. There is no indication that the Ryan amnesty is any better for Americans than the Senate amnesty. Amnesty is still a bad deal for all, whether it comes in one package from the Senate or in six packages from the House. The 1,200-page Senate bill is loaded with "slippery" words (such as "emergency," "comprehensive," "plan," and "reform") that create loopholes giving Barack Obama the opportunity to refuse to enforce any provisions he doesn't like, including border security that the public is demanding. That's exactly what Obama notoriously did to cancel provisions of several other laws, notably ObamaCare's date of enforcement and the effective Work requirement in Welfare Reform.
Listen to the radio commentary here: