Republicans can hardly believe their good fortune. First, Democratic Senator Byron Dorgan of North Dakota announced that he would not run for re-election, giving Republicans a good shot at taking his seat. Then the Democratic governor of Colorado, Bill Ritter, said he was bowing out. Ditto the Democrats’ top candidate for governor in Michigan. And all of it happened on the same day.The Democratic politicians’ decisions to step back both reflect and contribute to the party’s grim prospects this November. The weak economy and public anxiety about President Obama’s agenda are making Democrats think twice about running. But when they don’t run, they make the party’s predicament worse. The exception is when Democratic officeholders are in such bad shape that their retirement actually helps the party come up with a stronger candidate. It was good news for Democrats when Connecticut Senator Chris Dodd called it a career on the same day that his fellow Dems bowed out.