The death of New Jersey Senator Frank Lautenberg yesterday morning leaves the Democrats a vote down in the struggle to pass comprehensive immigration reform.

Lautenberg had been a champion of traditionally liberal causes. In fact, in April of this year, the 89-year-old left his hospital bed to trek into the Senate chambers in a wheelchair to cast what would be his last vote in Congress -- in favor of the gun control bill requiring background checks for firearms purchases, a measure that ultimately failed despite a huge public outcry.

Lautenberg's loyalties including immigration reform; he'd received a 100 percent rating from the American Immigration Lawyers Association. Backers of immigration reform has counted on his vote in the complicated math necessary amid the persistent threat of a Republican filibuster.

Without Lautenberg, the Democratic caucus drops to 55. Add in the four Republicans who are part of the Gang of Eight and there are 59 votes, still one short of the number required to end a filibuster.

Certainly, the loss of Lautenberg doesn't doom the measure. Some Republican senators aside from the Gang of Eight support immigration reform, but some Democrats are wary of it and may require concessions to secure their votes. That could complicate passage, particularly if some of those concessions come in the form of amendments to the bill, which would likely upset Republicans who are currently on the fence.

In addition, the Republican governor of New Jersey, Chris Christie, will appoint a replacement for Lautenberg. That's likely to be a Republican, as well, though Christie is a moderate, so he could appoint someone who also favors reform.

While the interim senator will only serve until a special election scheduled for Oct. 16, much of the debate will take place over the summer, so the Lautenberg's replacement could have the final say in the matter.

Of course, even if the Democrats can muster 60 votes, they were hoping for 70, to present a strong show of support for the bill before it heads over to the Republican-led House of Representatives, where passage is uncertain, and perhaps even unlikely.

That goal seems increasingly out of reach.