The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned.

The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned. But neither the United States nor any state shall assume or pay any debt or obligation incurred in aid of insurrection or rebellion against the United States, or any claim for the loss or emancipation of any slave; but all such debts, obligations and claims shall be held illegal and void.

The Congress shall have power to enforce, by appropriate legislation, the provisions of this article.

The Congress shall have power to lay and collect taxes, duties, imposts and excises, to pay the debts and provide for the common defense and general welfare of the United States; but all duties, imposts and excises shall be uniform throughout the United States;

To borrow money on the credit of the United States;

All bills for raising revenue shall originate in the House of Representatives; but the Senate may propose or concur with amendments as on other Bills.

The 14th amendment has never been applied in this context by any president so there is no precedent and no jurisprudence analyzing what specific authority Section 4 of the XIV amendment confers on the president with regards to the public debt. ...snip...

The 14th amendment was added post Civil War or as some southerners prefer, the War of Northern Aggression. The intent at the time was to declare that the US was not going to pay any debts incurred by the Confederacy, which had borrowed money from England and France to help in its secession efforts. So Section 4 confirmed that all U.S. public debt authorized by Congress was legitimate and declared that neither the U.S. nor any state would be responsible for paying any debts incurred by the Confederacy for the war or the loss of slaves. The Confederacy considered slaves to be property and made some noises about reimbursement for the loss of their property.

President Obama is currently throwing cold water on the idea that the Constitution will save America from the impending default crisis, but this view has some high-profile dissenters. Right-wing legal scholars Eric Posner and Adrian Vermeule made the argument that Obama can invoke the constitutional option in a New York Times op-ed published last week. Earlier this month, former President Bill Clinton said that if he was in Obama’s place, he would use the 14th amendment himself to raise the ceiling.

Our argument is not based on some obscure provision of the 14th amendment, but on the necessities of state, and on the president’s role as the ultimate guardian of the constitutional order, charged with taking care that the laws be faithfully executed.

When Abraham Lincoln suspended habeas corpus during the Civil War, he said that it was necessary to violate one law, lest all the laws but one fall into ruin. So too here: the president may need to violate the debt ceiling to prevent a catastrophe — whether a default on the debt or an enormous reduction in federal spending, which would throw the country back into recession. ...snip...

The 14th Amendment is a red herring, however; even if its debt provision did not exist, the president would derive authority from his paramount duty to ward off serious threats to the constitutional and economic system.

Mr. Obama needs to make clear that he will act unilaterally to raise the debt ceiling if Congress does not cooperate;

Federal law provides a variety of powers for the President to use in response to crisis, exigency, or emergency circumstances threatening the nation. Moreover, they are not limited to military or war situations. Some of these authorities, deriving from the Constitution or statutory law, are continuously available to the President with little or no qualification. Others—statutory delegations from Congress—exist on a standby basis and remain dormant until the President formally declares a national emergency. These delegations or grants of power authorize the President to meet the problems of governing effectively in times of crisis. Under the powers delegated by such statutes, the President may seize property, organize and control the means of production, seize commodities, assign military forces abroad, institute martial law, seize and control all transportation and communication, regulate the operation of private enterprise, restrict travel, and, in a variety of ways, control the lives of United States citizens. Furthermore, Congress may modify, rescind, or render dormant such delegated emergency authority.

The modern debt limit, in which an aggregate limit was applied to nearly all federal debt, was substantially established by Public Debt Acts passed in 1939 and 1941. The Treasury has been authorized by Congress to issue such debt as was needed to fund government operations (as authorized by each federal budget) as long as the total debt (excepting some small special classes) does not exceed a stated ceiling. Since 1979, the House of Representatives by rule has automatically raised the debt ceiling when passing a budget, except when the House votes to waive or repeal this rule.

It is quite common for US Presidents to issue executive orders that instruct federal agencies to promulgate administrative regulations in order to circumvent the legislative process in the US Congress altogether, though, as alluded to above, this can violate the US Constitution in a number of ways. US Presidents are quite aware that US congressional politics can defeat or otherwise prevent the passage of legislation presidents deem politically important.