David Weigel offers a post-mortem, as well as how it was her ability and willingness to work across the aisle that brought her down:
The post-election gloating over Murkowski’s problems revealed the problems conservatives had with her. She voted for the Troubled Asset Relief Program in 2008. In October 2009 she said she was “open” to compromise on cap-and-trade legislation if it expanded drilling and nuclear power. She had a moderate record on abortion, siding with liberals on some matters of federal funding for the procedure. And she occasionally spoke dismissively of Sarah Palin. Tell me if I’m missing something, but I think that’s it. Just like Sen. Bob Bennett (R-Utah), Murkowski wasn’t so much an unreliable vote, like Arlen Specter used to be, as a Republican in a safe seat who was too often approached for possible compromises by Democrats. And that was unacceptable.
You really have to admire the strategic chops of tea partyers in taking down Bennett and Murkowski. In both cases, they only had to convince a small number of partisans to oust their incumbents. In both cases, they could smooth the path to victory by adding new people to the electorate — in Utah that meant getting tea partyers to become Republican delegates, and in Alaska it meant activating some unaffiliated voters who could vote in the GOP primary. In Utah, they only needed to stop Bennett from getting to the final round of voting with around 3,500 delegates. In Alaska, they only needed to get a majority of around 102,000 voters to back Joe Miller. It reminds me of the foresight David Plouffe had in 2007 to make sure the Barack Obama campaign maximized its vote in small state caucuses, where big wins could net lopsided delegate margins.
At the end of the day, it seems being hyper-partisan is not a hurdle, but a benefit. I think that’s the story of this particular election season. Democrats are losing because they’re not partisan enough, as it would be practically impossible to do anything without some Republicans on board due to Senate rules. Republicans are winning because they don’t have to offer any solutions, and so get to be hyper-partisan. And the ones that aren’t are being shoved aside by shrewd calculus.