President Obama has now had his Nixonian "I'm not a crook" moment, taking to the airwaves to feign angry indignation about the Internal Revenue Service targeting his enemies while denying any knowledge whatsoever of what his administration had been up to.

I am not surprised that Obama is pretending - in careful language - not to know about the worst abuse of power by a presidential administration in a generation.

Why do I believe that Obama knew exactly what his IRS was up to (besides it being in the news for the last two years)? Because of the record of Steven T. Miller - the man Obama first hired and has now fired as acting commissioner of the IRS.

Make no mistake about it. When Obama appointed Miller, the president should have known what he was getting. Before becoming acting commissioner of the IRS, he was commissioner of the Tax Exempt and Government Entities Division, where, according to the IRS's faux-folksy website, "Steve oversaw the administration of tax law relating to employee plans, tax-exempt organizations and various government entities."

Perhaps the description should more accurately have read "oversaw and undermined the administration of tax law relating to ... tax exempt organizations." At Judicial Watch, we know this well because, very early on, we were one of the many conservative organizations and Clinton critics that Miller's tax exempt branch subjected to politically-inspired audits.

As The Washington Examiner's Paul Bedard reported recently in his "Washington Secrets" column, "Steven T. Miller, the acting IRS commissioner who managed the division that has admitted targeting anti-Obama Tea Party groups, was one of several agents who investigated anti-Clinton organizations, including Judicial Watch during that Democrat's administration, according to court documents and interviews."

As I relate in my book, "The Corruption Chronicles," when Judicial Watch complained about the audit and its political nature, an IRS official told us "What do you expect when you sue the president?"

Miller was one of the IRS officials who oversaw the invasive audit of Judicial Watch even while conceding that the audit "had created at least the appearance of a problem." It seemed every time we complained about the audit, Miller's bureaucrats expanded its scope until it covered seven years' worth of records!

So, now we find that Miller, despite this record of being a top official partly responsible for the last wave of IRS abuse during the Clinton years, was rewarded by Obama with the top position at the IRS. Given our well-publicized experience with him, it is no surprise to me that Miller was content to allow this illegal IRS harassment of Obama's hit list - and the subsequent cover-up.

Tom Fitton is president of Judicial Watch, an independent conservative government watchdog group based in Washington, D.C.