President Obama's health care law has eclipsed everything else his administration has done, sending his popularity to new lows. But in assessing the president's credibility, Americans should not forget two scandals that remain as important as his broken promises on health care reform.

A House oversight hearing on Thursday brought renewed attention to the IRS targeting of Tea Party groups from 2010 to the present. Catherine Engelbrecht testified that, after she applied for tax-exempt status for the King Street Patriots in Houston, four federal agencies that had completely ignored her family's business for 20 years began visiting, often. The alphabet soup of agencies that took sudden interest in Engelbrecht included OSHA (which saw a fork lift driver without a seat belt), the IRS (which audited her and her husband personally, as well as the business), the BATF (even though her business makes no gun parts), and the FBI.

Was this a coincidence? It's known that during this same period, the IRS was systematically harassing hundreds of other small Tea Party groups with intrusive, illegal questionnaires and unwarranted delays to their tax-status applications. Also consider the story of Jeff Black, a whistle-blowing former air marshall who years earlier revealed shoddy security practices to congressional investigators. Black was audited by the IRS on the very same day in June 2010 when the documentary “Please Remove Your Shoes” debuted in theaters, featuring him as a critic of the Transportation Security Administration.

It would seem more of a coincidence if there was no political motivation behind the treatment given Engelbrecht. Yet Obama told Bill O'Reilly in an interview that aired Super Bowl Sunday that there was “not even a smidgen of corruption” in the IRS's handling of conservative groups' applications – as if he had been there himself and knew the whole story.

Then there is the terrorist assault in Benghazi on a U.S. diplomatic post that left Ambassador Chris Stevens and three others dead on the anniversary of the 9/11 attacks in the U.S. A bipartisan Senate panel found last month that a competent administration would have heeded prior warning signs - including multiple other terrorist attacks in the area - and taken appropriate action to avoid a predictable and preventable disaster. Obama had unilaterally attacked Libya, and so he bore even more responsibility than did his predecessor in Iraq (who at least sought congressional permission).

Obama could not have been directly involved in the poor State Department decisions that weakened the consulate’s defenses. But after the fact, operating in an election year, he and senior aides took measures to deceive Americans about the facts behind Benghazi. For weeks before the 2012 presidential election, they discussed the attack as a spontaneous and inevitable result of Muslim rage over an offensive video trailer on YouTube.

But the evidence is overwhelming that the attack was a coordinated terrorist operation and it was known as such at the highest levels of the Obama administration within minutes after the bullets started flying. It's hard to see even a smidgen of credibility in Obama's Benghazi and IRS explanations.