The current senator from Colorado, Michael Bennet, did something he's never done before tonight: he won an election. He won by a good eight percentage points or so.
Good analysis is victory agnostic, so here are truths that would also have been true even if Andrew Romanoff had won:
(a) Democratic turnout was high (though a bit lower than Republican turnout) and a lot of voters waited until the last minute to decide. That suggests that allegiances and branding are ephemeral and voters are skeptical of slogans and campaign tactics.
(b) Romanoff is a career politician; Bennet was a career corporate strategist and education innovator; the insurgent had more of a base than the incumbent, who had barely been in office; the incumbent was more deeply connected to the status quo than the guy who had been a politician for most of his adult life.
(c) It is very hard to determine whether Barack Obama significantly helped Michael Bennet, or whether Democrats saw in his endorsement of Bennet the opportunity to send a message of disapproval to Democrats in Washington by voting for Romanoff. Plenty of Democrats knew Obama's choice and chose someone else -- someone who wasn't previously a Republican (like Arlen Specter) and who WAS fully embraced by the White House political machine.
(d) Bill Clinton's endorsement was the catalyst for Romanoff's surge. Given how well-known Romanoff was, the race should have always been closer than it was. Romanoff ran tough, hard ads against Bennet at the same time that he was basking in the glow of the Clinton endorsement and his own decision to sell his house to finance his campaign. Romanoff's ads against Bennet were over-the-top and may have backfired, because the trend was with him a week ago, and Bennet regained his footing in the last few days of the campaign. Bennet comes off as a likable, credible guy -- the more Democrats saw of him, especially as the campaign heated up, the more they liked his cool.
(e) Whoever won would be in a good position to keep the seat for Democrats given how divided and dysfunctional the state Republican Party has become, and given how itchy and potentially unattractive both Republican Senate candidates were.
Bennet's vote-by-mail operation and his ground game were stellar. A solid recipe: good campaigns run by competent strategists featuring strong candidates.
The Republican race is whisker-close: perhaps had Weld Co. District Attorney Ken Buck not stepped in manure by making fun of former Lt. Gov. Jane Norton's high-heeled promise to clean up Washington, his insurgent candidacy would be clear victories. Still, she had lots more money than he did and was the favorite going in. His surge -- and Romanoff's surge -- are evidence, yet again, that voters affiliated with parties feel less inclined to follow those parties' cues.
Disclosure: Michael Bennet is the brother of the editor of The Atlantic, James Bennet.