Maryland Gov. Martin O'Malley speaks to reporters on Wednesday. (AP Photo/Patrick Semansky)

Maryland Gov. Martin O’Malley (D) spearheaded an effort to gather signatures from fellow governors for a letter sent Wednesday to leaders of Congress urging an extension of emergency unemployment benefits for millions of Americans, his office said.

“In the past, Congress has extended unemployment benefits during similar economic downturns,” said the letter, which was signed by governors of 12 states and two U.S. territories. “Failure to extend it now would only halt our economic recovery and undo the progress that we have made since the height of the recent downturn.”

The letter, whose signers included the leaders of California and Illinois, noted that “many states continue to experience persistent levels of high unemployment.”

An estimated 1.3 million long-term unemployed workers lost their benefits on Dec. 28. Another roughly 1.9 million are at risk of exhausting their benefits later this year if Congress doesn’t act.

O’Malley, a former chairman of the Democratic Governors Association who is weighing a 2016 White House bid, acknowledged to reporters in Annapolis on Wednesday that all those who signed onto his letter are Democrats.

But, he added: “We welcome our Republican brothers and sisters to sign the letter as well.”