Last night, in the final debate before the 2016 SEC presidential primary on Tuesday, March 1st – commonly known as “Super Tuesday” – Republican US Senator Marco Rubio threw everything he had at Republican frontrunner Donald Trump.

Most of Senator Rubio’s attacks covered familiar ground, such as the Atlantic City bankruptcies and that Trump’s self-made narrative leaves out his rather bountiful inheritance. However, some of the attacks were new, and included dredging up a decades-old lawsuit regarding a subcontractor who used undocumented immigrant labor, and a current class-action lawsuit against now-defunct Trump University.

But soon after Rubio’s attack on Trump U, reporters began reminding people on social media that Senator Rubio had his own for-profit education scandal–one that not only involved fraud but a possible abuse of official power.

Landmine for Rubio in hitting Trump Univ—he once backed a for-profit college chain that shut down over mass fraud. https://t.co/U79EzGVSmy

— Sahil Kapur (@sahilkapur) February 26, 2016

On June 20th, 2014, Senator Marco Rubio wrote a letter to Jim Shelton, the deputy secretary of education, and Ted Mitchell, the undersecretary for post-secondary education, on behalf of Corinthian Colleges, Inc. a for-profit education company which was then under investigation for defrauding students.

In the official letter, Senator Rubio requested the Department of Education “demonstrate leniency” and allow Corinthian Colleges to continue to receive federal financial aid money while it was under investigation.

Less than a year after Rubio sent his letter, Corinthian Colleges, Inc. was fined $30 million by the Department of Education for “confirmed cases of misrepresentation of job placement rates to current and prospective students,” which hurt over 900 students.

After the 2014 fine, Corinthian College shut down and left 16,000 students without a school, but not before collecting $1.2 billion in federal student loans in its final year.

Some of that money found its way back to Rubio, whose PAC received $5,000 from Corinthian Colleges in that same year. Coincidence?

Senator Rubio may be a dilettante when it comes to his work in the Senate, but it is hard to believe he did not know in 2014 of Corinthian College Inc.’s terrible reputation. Rubio’s use of his official office to champion the interests of a corrupt campaign contributor makes him a less-than-perfect messenger to critique Trump University.

But given that Rubio is set to lose his home state to Trump, I guess he had to throw every rock he had, even if he’s living in a house with very thin glass.