michael_bennet_71U.S. Senator Michael Bennet—who will apparently face a long, tough battle for reelection, including a challenge from fellow Democrat Andrew Romanoff—has made a big change in his office, replacing Jeff Lane, his chief of staff, with Guy Cecil, a top political operative who served as the director of Hillary Clinton’s presidential campaign.

“Guy’s strong work ethic, leadership abilities, and strategic thinking will be a real asset,” Bennet (pictured) says in a statement to The Denver Post.

State Republican Party chairman Dick Wadhams claims the move illustrates that Bennet’s office is in “disarray.”

The Washington Post writes that Bennet is “among the most endangered Senators up for re-election in 2010.”

Meanwhile, former Lieutenant Governor Jane Norton has raised more than $500,000 in her bid to out-do fellow Republicans for a shot at facing Bennet, according to Congressional Quarterly. It seems certain, writes CQ, that Norton will be the best-funded GOP candidate in a slate of lesser-known candidates, such as Ken Buck, Weld County district attorney, and Ryan Frazier, an Aurora city councilman.