Every president in my voting lifetime has had problems during his administration that brought his leadership into serious question.
Eisenhower—health issues after heart attack
Kennedy—Bay of Pigs
Carter—hostage crisis and failed rescue attempt
Bush I—budget deficits, tax increase
Clinton—health care failure, Monica Lewinsky
Bush II—no WMD's in Iraq, financial crisis
Obama—press surveillance and IRS abuse
Those problems facing President Obama right now appear to be on the tipping point of threatening his presidency. Given Obama's tendency to avoid explaining anything to the public and the anger of the press at being mistreated, his moral authority and approval ratings may erode past recovery, taking along the possibility of working out a fiscal compromise or passing the immigration reform bill developed by eight senators.
I think he needs to fire Eric Holder and shake up the Justice Department to save himself, but I doubt he will do that. However, if he does not act with some force, he may give the Republicans the Senate in 2014 and they will proceed with great enthusiasm to repeal Obamacare and slash the budget so that Obama is left with no legacy whatever and the country is left with a government inadequate to its needs.