Democrat Rutt Bridges’ surprise announcement yesterday that he was withdrawing from the race for governor essentially makes the field wide open again on the Democratic side, and the new race to see who will jump in first has begun.

The Republican field is essentially set with Rep. Bob Beauprez and former DU President Marc Holtzman battling it out. Former Rep. Scott McInnis might still enter the race, but at this point that only seems likely if Holtzman or Beauprez screw up.

On the Democratic side, former Denver DA Bill Ritter is now the only declared candidate, but most observers don’t expect that to last for long. Ritter has many potential strengths, but he is not perceived by insiders to be a slam-dunk candidate and will not likely scare off potential new candidates. State Senator Joan Fitz-Gerald has been contemplating a run for governor since Steve Adams, the head of the Colorado AFL-CIO, publicly called for her to run back in May. Fitz-Gerald was thought to be undecided as recently as yesterday morning, but with Bridges — who was the Democratic frontrunner — out of the race, the road to the Democratic nomination just got a lot easier.

There should also be a barrage of new calls for Denver Mayor John Hickenlooper to run now that Bridges is out. Hickenlooper and Bridges are good pals, and the Mayor would not have been enthusiastic about running against his friend. There are mixed opinions on whether or not Hickenlooper even wants to run for governor, but party leaders, elected officials and major donors will certainly be calling him again asking him to run (as they had been doing last spring before Hickenlooper gave way to Bridges).

Speaker of the House Andrew Romanoff will again be on the short list of candidates, and there was some speculation yesterday that Rep. Mark Udall could reconsider running for governor. Udall declined to run for governor in an announcement last winter, instead saying that he would run for the U.S. Senate in 2008. While it’s probably not likely that Udall would change his mind again and run for governor, it’s not out of the realm of possibility.

Whoever emerges as a new candidate for the Democrats, it will likely happen fairly soon. The first of these four names — Hickenlooper, Fitz-Gerald, Romanoff and Udall — to announce a candidacy will probably be the last, because it’s unlikely that two of those four would run against each other.

Bridges is reportedly not prepared to endorse another Democrat at this point, but his classy withdrawal from the race, in which he spoke candidly and honestly about his own personal decision not to run, clears the way for another candidate to make an easy entrance into the race. Bridges’ graceful exit may actually make him more powerful of a figure than he was as a candidate in the short term, because his endorsement now takes on a greater importance. It’s perhaps bittersweet that his honest withdrawal showed him to be the kind of straight-talking candidate that Colorado voters might have loved.