The Washington Post's Aaron Blake looks at Sen. Michael Bennet's first general election ad, which attacks his opponent Ken Buck on entitlement programs and abortion exemptions. Bennet's choice to run a negative ad right out of the gate rather than one introducing himself to voters signifies a new reality for Democrats, Blake explains:

Take three more examples from Tuesday's primaries: Rep. Kendrick Meek (D-Fla.) and Sens. John McCain (R-Ariz.) and Lisa Murkowski (R-Alaska).

Meek's first primary ad hit businessman Jeff Greene hard -- setting the tone for a convincing primary win despite being heavily outspent.

On the GOP side, McCain used a $21 million blitz featuring mostly negative ads to destroy former Rep. J.D. Hayworth. He won easily.

Meanwhile, Murkowski held her fire against attorney Joe Miller until the last 24 hours of the primary and it appears to have cost her a Senate seat. (Caveat: There are still thousands of uncounted absentee ballots and a recount could follow once the counting is completed.)

Democratic Senate candidates are, not surprisingly, taking the McCain rather than the Murkowski approach.

Blake goes on to list a string of Democrats who have attacked their opponents from the get-go. Harry Reid, Paul Hodes, Robin Carnahan, Blanche Lincoln -- they're all catching on to the necessity of negativity.

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