WASHINGTON - August 25 - Sen. Bernie Sanders (I-Vt.) and Rep. Peter DeFazio (D-Ore.) today urged President Barack Obama to dismiss a co-chairman of a White House advisory commission on budget deficits who compared Social Security to "a milk cow with 310 million tits."

Citing the "insulting" remarks by former Sen. Alan K. Simpson, Sanders and DeFazio asked the president to remove Simpson from the National Commission on Fiscal Responsibility and Reform, which is charged with making recommendations on federal budget deficits that could affect Social Security.

"While there are honest differences of opinion as to how best to tackle this growing problem, we should all be in agreement that everyone working in this area - especially someone in as important a position as the co-chair of your National Commission on Fiscal Responsibility and Reform - has a responsibility to be as serious, deliberate, and sober as the challenges we face," they wrote in a letter to the president.

Simpson's remark was included in an e-mail to the director of Older Women's League. "I've made some plenty smart cracks about people on Social Security who milk it to the last degree," the former Wyoming senator wrote to Ashley Carson. "You know 'em too. It's the same with any system in America. We've reached a point now where it's like a milk cow with 310 million tits!"

Sanders and DeFazio called the comments "beyond comprehension" and "demeaning" to the senior citizens, the disabled, widows and orphans who depend on Social Security.

"Despite the many years of distinguished public service former Senator Simpson has dedicated to this country, his recent e-mail indicates that it is no longer appropriate for him to serve on the bi-partisan deficit reduction commission," Sanders and DeFazio wrote. "Therefore, in order for your commission's recommendations to have credibility with Congress, we respectfully urge you to remove Senator Simpson from the commission."

Referring to the $13 trillion national debt, Sanders and DeFazio told the president that they look forward to working with him on ways to address "serious long-term fiscal challenges that require thoughtful and difficult solutions." As leading defenders of Social Security in Congress, they underscored that Social Security is strong and stable.

"Let's be clear: Social Security is not going bankrupt, nor has it contributed one dime to the federal deficit. For 75 years, through good times and bad, Social Security has paid out every benefit owed to every eligible Americans and will continue to pay 100 percent of those benefits through 2037, according to the Social Security Board of Trustees, and until 2039, according to the Congressional Budget Office. In fact, the Social Security Trust Fund today has a $2.5 trillion dollar surplus which is projected to grow to more than $4 trillion by the year 2023."

Sanders and DeFazio also noted that Social Security provides the majority of income for two-thirds of the nation's elderly and, for one-third, it provides nearly all their income.

In an Aug. 6 letter to the deficit commission, Sanders and DeFazio urged the panel to reject proposals to raise the Social Security retirement age to 70.