One of President Barack Obama’s most enthusiastic supporters, Harvard Law professor Laurence Tribe, said on Friday the ...

One of President Barack Obama’s most enthusiastic supporters, Harvard Law professor Laurence Tribe, said on Friday the White House and Congress can’t fall back on the 14th Amendment to make an end run around the current debt crisis.

Writing on the New York Times op-ed page, Tribe, who once called Obama the “best student I ever had,” said the idea that a president can use the 14th Amendment to borrow money without regard to Congress provides “the false hope of a legal answer that obviates the need for a real solution.”

“Several law professors and senators, and even Treasury Secretary Timothy F. Geithner, have suggested that section 4 of the 14th Amendment, known as the public debt clause, might provide a silver bullet,” Tribe said. “This provision states that ‘the validity of the public debt of the United States, authorized by law … shall not be questioned.’ They argue that the public debt clause is sufficient to nullify the ceiling — or can be used to permit the president to borrow money without regard to the ceiling.”

But the president has very little authority to borrow money, Tribe wrote, without explicit approval from Congress, especially if Congress forbids it.

“The Constitution grants only Congress — not the president — the power ‘to borrow money on the credit of the United States,’” Tribe wrote. “Nothing in the 14th Amendment or in any other constitutional provision suggests that the president may usurp legislative power to prevent a violation of the Constitution. Moreover, it is well established that the president’s power drops to what Justice Robert H. Jackson called its “lowest ebb” when exercised against the express will of Congress.”

And while many liberals are urging Obama to stand ground against cuts to Social Security and Medicare and Medicaid benefits, Tribe writes that the president must compromise.

He wrote: “Only political courage and compromise, coupled with adherence to traditions that call upon Congress to fulfill its unique constitutional duty, can avert an impending crisis.”

The op-ed is not the first time Tribe has taken an indirect shot at his former pupil’s administration.

In April he signed a letter in the New York Review of Books and gave an interview to the Guardian of London decrying the treatment of Wikileaks suspect Bradley Manning. He also trashed now-Supreme Court Justice Sonya Sotomayor in a 2009 letter sent three weeks before her nomination, dubbing her “not nearly as smart as she seems to think she is.”

Tribe later said he had since changed his mind about Sotomayor.