A few days ago, I authored a post noting that Colorado's appointed Senator Michael Bennet was vulnerable against some relatively no-name opponents (although upon further review, both opponents brought some real strengths to the table).  To be sure, part of Bennet's problem is that he was relatively unknown -- googling him returns more hits about the dancer and the football player than it does about the Senator.  Presumably he has more room for growth than most incumbents who find themselves under 50%.

At any rate, he will have a top-notch opponent later this week.  The Denver Post's Dan Haley reports:

The Republican contest for Colorado's U.S. Senate seat so far has been like a NASCAR race in a mud bog. Lots of shiny race cars revving their engines, but no one gaining any real traction.

Enter new driver Jane Norton, the former lieutenant governor and half of a GOP power couple. (Her husband, Mike, is a former U.S. attorney who ran for Congress in the 1980s.)

Last week, Norton — no, not Gale Norton or Kay Norton — filed paperwork to form an exploratory committee. Even though she has no voting record and no readily known stances on hot-button issues — one insider even admitted she can't remember what Norton's voice sounds like — the former lite guv will be a game-changer in the crowded primary field. That is, if conservatives decide that winning is more important than past indiscretions. (More on that in a bit.)

Norton is a protege of former Governor Bill Owens, who is conservative but has endorsed some tax hikes and other measures that are anathema to movement conservatives.  Norton herself is something of a blank slate, so she can tailor many of her positions as she sees fit.  This turns the race into a top-tier event.