By Timothy Gardner

WASHINGTON (Reuters) - President Barack Obama cut short the prison terms of 214 convicts on Wednesday, the largest number of commutations a U.S. leader has granted in single day since at least 1900, the White House said.

Obama has now granted a total of 562 commutations during his presidency, more than the number by the past nine presidents combined, it said. In Wednesday's batch, 67 convicts were serving life sentences.

The convicts were serving time for crimes including possession of crack cocaine and methamphetamine, with intent to distribute. Some were imprisoned on charges of gun possession.

One of the convicts, James Wright of Baltimore, Maryland, was serving a 20 year sentence that began in 2006 for possession of crack with intent to distribute. He will be released in December.

Obama has worked to reform the U.S. criminal justice system and reduce the number of people serving long sentences for nonviolent drug offences. It is a rare issue on which Obama gets support from Republican lawmakers.

For years crack offenders faced stiffer penalties than powder cocaine offenders, even though the substances are similar at the molecular level. Critics have said the disparity has unfairly harmed minority and poor communities.

In 2014, Obama announced the most ambitious clemency program in 40 years, inviting thousands of drug offenders and other convicts to seek early release. But the program has struggled under a flood of unprocessed cases.

"Our work is far from finished," White House counsel Neil Eggleston said about the commutations. Eggleston urged Congress to take action. "While we continue to work to act on as many clemency applications as possible, only legislation can bring about lasting change to the federal system," he said.

The program automatically expires when Obama leaves office next January and it is uncertain whether the next president would continue with a similar plan. Donald Trump, the Republican candidate in the Nov. 8 election, has championed "law and order" in his campaign. Democrat Hillary Clinton has called for criminal justice reform.

(Reporting by Timothy Gardner and Ayesha Rascoe; Editing by Andrew Hay and Steve Orlofsky)