Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" and "Governing America."

Princeton, New Jersey (CNN) -- On "The Daily Show," Jon Stewart captured the frustration that many of President Obama's supporters have felt over the past week as one scandal after another cascaded into the White House.

After starting with a predictable riff accusing Bill O'Reilly of ignoring facts when attacking the Obama administration, Stewart turned to the IRS story, banged on his desk, and yelled out curses....

Many liberal Democrats were frustrated and shocked that the administration had permitted the seizure of the phone records, the kind of activities they would certainly have railed against had they happened under President George W. Bush.

Although there is no evidence that Obama was involved in either of these incidents -- and many Republicans are clearly trying to use them to drum up a narrative about a scandal-ridden presidency -- the combination left many Democrats, like Stewart, scratching their heads, wondering what happened to the president who promised when he ran in 2008 to transform the way politics worked....