Against his doctor's advice, a stooped and feeble Sen. Mario Gallegos arrives at the Texas legislature each day, just to make sure lawmakers do not take up a bill requiring voters to show identification proving they are not illegal immigrants.

And when the rigors of the job start to wear on the Democratic lawmaker, whose body is trying to reject a liver transplanted four months ago, he retires to a hospital-style bed — donated by a Republican colleague — in a room next to the Senate chamber.

From there, he can be summoned at a moment's notice should his vote be needed to keep the bill from reaching the floor.

In a life-and-death drama playing out in the legislature, Gallegos is putting his health at risk to block a measure he and others say could prevent many minorities and the elderly from taking part in elections in Texas.

"If there was enough votes to block, I promise I wouldn't be here," he said from his bed, his slumped shoulders and tired, jaundiced eyes making him look much older than his 56 years. The once-burly lawmaker is now thin and his skin hangs loose.

The Republicans pushing the voter ID bill say illegal immigrants are voting in Texas elections and must be stopped. But Democrats say thousands of legal residents will lose the right to vote because they lack proper identification. Opponents of the measure — including Gallegos, a Mexican-American — say minorities, the elderly and the poor are less likely than others to have driver's licenses or other documents.

In the Texas Senate, bills cannot move forward unless 21 of the 31 senators vote to bring them up for debate. The Democrats hold 11 seats, just enough to block a bill if they stick together.

Gallegos, a recovering alcoholic whose liver was ruined by drinking, received the transplant two weeks into the five-month legislative session that ends on Monday. He returned to the Capitol 13 weeks later just to stop the voter ID bill.

Now he is dealing with symptoms of organ rejection and the exhaustion of the job.

He is taking medication to keep the organ rejection under control. But his doctors say he should be resting and should be within 100 miles of the hospital where he received the transplant in case something goes wrong. The state capitol in Austin is about 160 miles from his hospital in Houston.

Most of Gallegos' Houston-area constituents are black or Hispanic, and about a quarter of them live in poverty. About one in five speak little or no English.

So the retired firefighter starts his mornings with 10 pills and a visit to the legislature's nurse to check his blood glucose levels. He visits the nurse for similar blood tests twice more throughout the day, and periodically gives himself shots of insulin.

Then it is another seven pills before crashing into bed at his Austin apartment at about 8 p.m.

When the Senate is in session, he sometimes retires to his bed in the sergeant-at-arms' office, where it is quiet enough to get some rest.

"I just want to take care of him," said Republican Sen. Robert Deuell, who provided the bed and is also a family physician. "He's going to come one way or another, so I just figured I'd make it easy for him."

It is a far cry from the past eight sessions Gallegos spent in Austin, before his heavy drinking led to an intervention by his Senate colleagues. He quit drinking and went into rehab last spring.

Under what is known as the Luna Precedent, named for a lawmaker who was hospitalized in the 1990s, legislators can ask for 24-hour notice that a bill is about to come up. Gallegos was given such notice early this month. But lawmakers can invoke the Luna Precedent only once during a session.

Gallegos' Republican colleagues agreed not to bring up the bill last Friday when he was in Houston for a biopsy that determined his liver was not infected. That act of courtesy followed days of rancor over Republican Lt. Gov. David Dewhurst's unsuccessful effort to push the bill through when another Democrat came down with the stomach flu.

Deuell said waiting was "just the decent thing to do."

"I hope he lives, but if for some reason he wouldn't, I couldn't in good conscience have him die thinking he failed," he said.