A number of Democrats are on board as well. Last year,  Mark Warner, the ranking Democratic member of the securities, insurance and investment subcommittee of the Senate Banking Committee, pushed then-Treasury counselor Antonio Weiss on why the U.S. wasn’t selling ultra-longs. He hasn’t changed his tune.

“If there is an appetite for long-term debt in foreign markets and with U.S. corporations and universities, there would be sufficient appetite to market the debt of the world’s safe-haven and reserve currency,” Warner said in an emailed reply to questions.

For the naysayers, the case against ultra-longs rests on two basic concerns: liquidity and cost. Regular and predictable auctions have been a pillar of the Treasury’s debt management since the 1970s, and a key reason the U.S. bond market has become the deepest and most important in the world.

Finding Buyers

Finding enough demand to issue 50-year bonds on a regular basis and move the needle in the $13.9 trillion market could be a challenge and potentially cost taxpayers billions of dollars. Insurers and pensions, the most likely buyers, are prone to hold to maturity, which means the securities may not be readily available to trade. If anything, many say issuing ultra-longs makes more sense politically than it does financially or structurally.

A 50-year bond would likely yield about 0.2 percentage points more than 30-year Treasuries, according to JPMorgan Chase, whose analysts said such sales aren’t a good idea.

David Mericle, an economist at Goldman Sachs, said in a report last week that he doesn’t expect the Treasury to sell ultra-long term debt partly because it’s “likely to again receive skeptical feedback from dealers.” Nomura also said the Treasury needs to do a “deep and comprehensive analysis” before trying such sales because it isn’t clear whether the benefits would outweigh the costs. Morgan Stanley warned in an April 21 report that “investor demand for ultra-long issuance will not be robust enough.”

Such criticisms have become more muted as the odds increase that the administration will issue ultra-long bonds. While a number of dealers, ex-Treasury officials and former members of the Treasury Borrowing Advisory Committee still voice concerns off the record, few would do so publicly. Most say the Treasury will probably sell the debt anyway.

Political Decisions

Whatever the case, big Treasury decisions are often political decisions. Under Larry Summers, the department introduced inflation-linked bonds, known as TIPS, in 1997 to provide policy makers a market-based gauge of inflation expectations, even though studies have shown they ended up costing taxpayers billions in extra interest. Former Treasury Undersecretary Peter Fisher ended sales of the 30-year bond in 2001, only to see it revived in 2006 as the war in Iraq and the Bush administration’s tax cuts caused record budget deficits.