WASHINGTON (CNN) -- Chief Justice William Rehnquist, who helped shift the U.S. Supreme Court toward a more conservative ideology and strongly supported states' rights during his three decades on the bench, has died.

Rehnquist, who presided over the court for nearly 19 years, was 80.

Rehnquist, who had been receiving chemotherapy and radiation for thyroid cancer, died at an Arlington, Virginia, hospital surrounded by his three children, a court spokeswoman said.

He was working in his office until a few weeks ago," CNN Producer Bill Mears said.

"He loved his job and continued to work until the very end," he added.