Quoting from this site:
In previous years, the scandal might never have surfaced. When eight U.S. attorneys were ousted in early December, the administration cited poor performance as the reason. But California Sen. Dianne Feinstein and other Democrats started raising questions about the firings. Hearings were called, administration records were requested and the fired U.S. attorneys were called to testify. The media started getting leaks suggesting top GOP lawmakers had improperly pressured some of the prosecutors to investigate Democrats.
“It normally would have just been swept under the rug,” said Rep. Debbie Wasserman Schultz, D-Fla. “The administration would have just tried to ride it out. But now that we have a Democratic Congress, they can’t do that anymore.”
Thank God for the wisdom of the men who laid out our government. Checks and balances. It’s a crummy way to get things done, efficiency-wise–but it’s a hell of a way to run a country.