Sens. Michael Bennet* and John McCain are both well-funded incumbents facing challenges from the more extreme wings of their parties. In response, McCain lashed out very early on, pouring more than $15 million into attacking Tea Party-backed opponent J.D. Hayworth. But according to Felicia Somnez at The Fix, Bennet "waited to go negative against his primary opponent" -- and may be kicking himself for it: 

He has spent a staggering $5.8 million on the race, but his first mention of Romanoff in a TV ad came only two weeks ago; until then, Bennet's spots were largely positive ones, including one that features his three young daughters and drives home the message that Bennet is out to "clean up Washington."

With polls showing Romanoff now tied with Bennet -- a Denver Post poll released last weekend had Romanoff at 48 percent and Bennet at 45 percent -- some observers are wondering whether Bennet might have been better served by pursuing a McCain-style "scorched-earth" strategy against his upstart primary opponent.

One Democratic operative who has been following the campaign closely but is neutral in the race called the Bennet camp's strategy "horrendous."

"I've never seen anything quite this disastrous," said the source, who requested anonymity in order to speak candidly about the race. "They wasted money; they wasted time. They let Andrew define this race."

The operative added that while Romanoff is running as a crusader against PAC and lobbyist money, "the absurdity of it is that Andrew's message is based on something that's not accurate."

"The only reason Andrew's in this is frankly because of Bennet's failures," the operative said.

McCain has fared better, recently polling 20 points ahead of Hayworth. It's worth noting, however, that McCain had over two decades of Senate experience (and a high-profile presidential campaign) under his belt going into this race, whereas Bennet was appointed just last year.

Read the full story at the Washington Post's blog The Fix.

*NB: Michael Bennet is the brother of James Bennet, editor of The Atlantic.