Congressman Mark Udall officially launched his campaign for U.S. Senate today with a four-day bus tour around the state. Udall will face former Rep. Bob Schaffer in November. A tight race is expected. While Republicans still outnumber Democrats in Colorado, the state has been trending towards Democrats in recent years. This looks like a good year for Democrats due to disenchantment with President Bush, the war and the economy. Udall also will get a boost from Senator Ken Salazar. In 2004, Udall planned to run for Senate but withdrew when the party rallied around the more moderate Salazar. Another factor in Udall's favor: He's been the "green" candidate for a long time, making renewable energy a chief priority. He's also buffed up his foreign policy experience through his service on the House Armed Services Committee. And, he's reached out to ranchers and sportsmen. Experts say the key to whether Udall can win is in District 3 -- the 29 rural counties on the Western Slope and in Southern Colorado -- and in gaining the Independent vote. Colorado has a total of 42 rural counties. Other places Udall needs to do well are Larimer, Jefferson and Arapahoe. Larimer is in District 4 and is Schaffer's old district. I think Udall will benefit from the Democratic convention being held in Denver. Coloradans will be inundated with coverage of the event and he likely will have a prominent role with a lot of media exposure. Overall, things look good for Udall. Still, it's not a slam dunk and Schaffer and the Republicans will put up a big fight -- even on the tiniest of issues, like Udall's zip code. Their best shot is portraying Udall as the "classic liberal" and even that's problematic as Udall has spent the past four years moving towards the center. Their second best shot imay be coat-tails -- if John McCain takes Colorado, he may provide down-ticket support for Schaffer. All in all, this will be a most interesting race to watch.