An increase in the Medicare eligibility age, perhaps more than any other proposal getting bandied about in the fiscal cliff talks, would split President Barack Obama from the heart of his political base.

Rep. Emanuel Cleaver II, D-Mo., the chairman of the Congressional Black Caucus, told CQ Roll Call last week that his caucus has been supportive of the president, but he said raising the Medicare eligibility age from 65 to 67 would present a tough choice between backing the president and protecting African-American seniors from bearing the brunt of the change.

As Cleaver noted, African-Americans have much lower life expectancy than whites, so later eligibility affects them far more.

“We obviously have been extremely supportive of the president and we have been the past four years to be sure,” he said. “We would be in a really, really awkward situation if the president made such a proposal.”

The Missouri Democrat said it would be “a request for us to vote against many of our constituents.”

African-American males have an average life expectancy of 71.6 years, compared with 76.4 years for non-Hispanic white men, according to preliminary data for 2011 from the Centers for Disease Control and Prevention. African-American women have a life expectancy of 77.8 years, versus 81.1 years for non-Hispanic white women.

Still, Cleaver noted that the CBC is also pushing for many of the other things Obama wants in a year-end package, including his $50 billion infrastructure request and other job creation items.

“It would not be a fun time to be the chair,” if those items were included alongside the Medicare age, he said.

Cleaver, more broadly, said that the fiscal cliff debate shows he was right in 2011 when he labeled the debt deal a “sugar-coated Satan sandwich” in an interview with CQ Roll Call. “You can see now why it was [a Satan sandwich],” he said. “Because, you know, initially it looked, like sin. It initially looked delicious. Once you start eating on it, peeling back the buns,” he said, you find nothing but “negativity.”

“What did we settle? Nothing. We’re still arguing over the debt ceiling, we’re still arguing over whether Medicare and Social Security should be altered,” he added.

Senate Majority Whip Richard J. Durbin, D-Ill., also has thrown cold water on the Medicare age idea — saying he had been told that the White House had taken it off the table. He later clarified that he hadn’t heard that directly from the White House.

Durbin said he would not support an age increase without a guarantee of affordable coverage for the affected seniors. “Until we come up with gap coverage, I don’t think it’s a viable option,” he said.

On Thursday, 73 House Democrats sent a letter to the president urging him to not raise the age — although Obama did not rule it out in an interview with ABC News’ Barbara Walters.

The president questioned how much the move would save. The Congressional Budget Office has scored a gradual increase to age 67 as saving Medicare $148 billion in the first decade.

Of course, Obama already agreed to the idea as part of the 2011 grand bargain talks, and the fact that the administration has not agreed to the idea this time around has been a source of frustration in GOP circles. A House Republican aide said Dec. 14 that they have proposed the increase in the negotiations.

But White House Press Secretary Jay Carney contended that Republicans had yet to offer a single specific spending cut or revenue hike during the talks.

Emily Ethridge contributed to this report.