Mr. Lautenberg, a New Jersey Democrat and the oldest member of the Senate at 89, has been out for weeks dealing with health complications partly from cancer treatment he received several years ago. But with Democrats scrambling to come up with enough votes to overcome resistance to the most sweeping gun-control legislation in a generation, Mr. Lautenberg’s presence (or absence) is shaping up to be critically important. Aides insist that Mr. Lautenberg, who has been undergoing physical therapy for weeks, will try to get to Washington once the voting begins on the assortment of gun-safety measures, which are expected to come to the floor in the coming weeks. Mr. Lautenberg’s aides say he is eager to return, particularly given that he introduced an amendment to ban high-capacity ammunition magazines. “Senator Lautenberg is feeling better and hopes to be in Washington for gun votes,” Caley Gray, a spokesman for the senator, said in a statement on Monday. For weeks, rumors and concern have been swirling about the health of Mr. Lautenberg, who this year announced that he would retire rather than seek a sixth term in 2014. The senator cast his most recent vote in the Senate on Feb. 28. The preoccupation with Mr. Lautenberg, one of the chamber’s most ardent advocates of gun control, has only intensified as the Senate moved in recent days to begin the most significant debate on gun legislation in two decades. For the last few weeks, Mr. Lautenberg, who received a diagnosis of stomach cancer three years ago, has been grappling with debilitating and long-term consequences that powerful chemotherapy treatment has had on his leg muscles, according to people close to him. As a result, he has been using a wheelchair while undergoing physical therapy to regain his strength. But Mr. Lautenberg, an extraordinarily proud man who served in World War II, has not wanted to show up in the Senate in a wheelchair, according to those who know him. For Democrats, the interest in Mr. Lautenberg’s health goes far beyond the coming votes on gun legislation. Should Mr. Lautenberg decide to retire before his term ends, his departure could have a significant impact on the balance of power in the Senate, where Democrats hold 53 seats and are typically joined by two independents. Gov. Chris Christie of New Jersey, a Republican, would have the legal authority to make an interim appointment to the seat. And he would almost certainly select a Republican, depriving Democrats of a crucial vote in the Senate.
