Hillary Clinton is said to be frustrated with her lack of authority as secretary of state and resentful of the glacial pace of the White House vetting process. "President Obama's picks fly in even if they didn't pay their taxes. But her picks take forever," noted one Democrat. "Plus, she has no real clout over Holbrooke or Mitchell." Richard Holbrooke is Obama's "special representative" for Afghanistan and Pakistan. George Mitchell is "special envoy" to the Middle East. Clinton is said to be considering quitting to retake her old US Senate seat now held by Kristin Gillibrand -- or running for governor, as one rumor has it. "Her argument will be that Gillibrand is in danger of losing the seat to the Republicans," said a source. But Gillibrand won't voluntarily step aside, unlike Rep. Nita Lowey, whom Clinton nudged out of the race in 2000. "You couldn't blow Gillibrand out of that seat with dynamite," said our source. Clinton's rep did not get back to us by deadline.