This vote was on a motion to preserve an amendment offered by Hillary Clinton, D-N.Y., that would expand the definition of "immediate relative" in the context of visa applications. The amendment, Clinton said, would have the effect of exempting from current visa caps spouses and minor children of lawful permanent U.S. residents.

"This amendment is necessary because the compromise bill does absolutely nothing to bring these families together. In fact, the compromise actually reduces the number of visas for spouses and minor children of lawful permanent residents. It does not allocate a single visa to address the existing backlog for these family members," Clinton said.

Arlen Specter, R-Pa., said Clinton's amendment has some merit but that it would jeopardize the carefully constructed bipartisan compromise that allowed the underlying bill to be brought to the floor at all. The amendment was offered to a bill intended to overhaul America's immigration system. Among other things, the bill establishes several new temporary and permanent visas in an effort to encourage the estimated 12 million illegal immigrants living in the United States to legitimize their residency.

Specter also said that the amendment would have the effect of allowing each of the estimated 800,000 legal permanent residents or green card holders the right to immediately bring over their spouses and children. Specter said while he prefers those families to be reunited, having them all enter at once would be problematic.

Opponents of Clinton's amendment raised a parliamentary move (called a "point of order") in an attempt to defeat the amendment. A "point of order" is a procedural motion senators may bring up when they feel a bill, amendment or other motion violates certain rules set out by Congress to govern itself. Unless senators vote to waive those rules – which usually takes 60 votes, a large margin in the Senate -- the bill, amendment or motion in question can be killed by the point of order.

A point of order was raised against Clinton's amendment as violating the Senate's rule known as PAYGO, which requires any legislation that creates new spending or reduces revenues be offset by a reduction in spending, or creation of new revenue. Ted Kennedy, D-Mass., called a vote on waiving those rules and allowing her amendment to go forward.

The waiver motion was rejected 44-53. Every Republican voted against the waiver motion. All but five Democrats voted for the waiver motion. Thus, the motion to waive the rules was defeated, and as a result Clinton's amendment was killed. The bill went forward without language that would have expanded the definition of "immediate relative" to include minor children and spouses of lawful permanent residents.